Wrong. At the point where he has enough feats to do this, the Fighter would need to have magical gear allowing him to be effective with all of those styles. Unless the DM is giving out truckloads of items and gold to the Fighter to help him out, he is still going to only be doing one thing well.
I respectfully disagree. I always considered two +2 weapons better than one +3 weapon, considering that I was spending approximately the same amount of money. With 3.5's changes to DR, this is even more true. I can understand if you personally want to be armed with one +4 weapon and nothing else, but please don't assume that your strategy is the only viable one.
First, the Fighter is only useful in narrow combat situations. All the classes you just admitted are better than a Fighter in various combat styles completely blow the Fighter away in social situations, survival situations, or stealth situations. Furthermore, D&D is a game of specialization. Generalization weakens a character, making them ineffecient compared to those who specialize. The fact that you claim the Fighter needs to be generalized is merely proving the point that the class is underpowered.
"Narrow combat situations" is an oxymoron in D&D. If you've built yourself an extremely specialized fighter and he's doing well in every combat, then your DM is either stupid, unimaginative, or very very forgiving of the fact that you've specialized yourself into a niche.
As for what I admitted, I'd appreciate you not twisting my words. What I said was that a member of one of those classes who specialized in a class-favored style (hit-and-run for rogues, tanking for barbarians, archery or two-weapon fighting for rangers) would outfight a
generalist fighter using that same style. A fighter specializing in one of those styles will do just as well, generally speaking, as his class-specialized counterpart. We've seen enough arguments and counterarguments about the barbarian versus the fighter in tanking contests that it's obvious, to me at least, that they are close enough to be considered approximately equal.
So what I said was:
Generalist Fighter is more flexible than Specialist Ranger/Rogue/Barbarian, but not as good as the R/R/B in the area that the R/R/B specializes in.
Specialist Fighter is just as good as the R/R/B in that area.
As for your "they totally trounce the fighter in other areas" argument, I don't see at all how the Ranger beats the Fighter socially, the Barbarian beats the Fighter at stealth, or the Rogue beats the Fighter in survival situations.

Oh, wait, you want me to compare the Barbarian's Survival -- his biggest strong point -- to the Fighter's? Well, um, duh. Yes, the fighter also fails to turn undead or cast spells. He is not as alert as the ranger or rogue, the TWO core classes that get spot. Congratulations.
It seems like this argument is devolving into an endless series of repetitions of basic premises. One side feels that the fighter is more powerful in combat, and is therefore balanced by being weakest out of combat -- and that people who want a fighting-person who is also gifted with social graces should multiclass. The other side either denies that the fighter is more powerful in combat (and I'm happy to continue arguing against that one) or says that fighters are only a
little more powerful in combat but are a
lot less powerful out of it.
I'd say that whether or not that's still balanced probably depends on your campaign. The designers obviously felt that combat was important enough that a minor combat advantage had to be balanced with a major out-of-combat disadvantage.
For example:
PC:A gets a class ability that gives a +2 to hit.
PC:B gets a class ability gives a +2 to diplomacy checks
After one year in the campaign, the numbers are as follows:
PC:A -- has made 1,000 to-hit rolls. Benefit of +2000 over a year
PC:B has made 100 diplomacy checks. Benefit of +200 over a year
If that math is true, then from a pure "getting bonuses" standpoint, PC:A has gotten a lot more out of that class ability. From a game standpoint, it's possible that he spent most of those rolls attacking unimportant stuff, while every time PC:B uses his diplomacy skill, it was for something vital to the plot -- but it's also possible that PC:B was improving his standard with the barmaids while PC:A was whacking BBEGs left and right. We don't know. That's a much more complex equation -- and I'm a former English Major.
I chose those numbers because it's obvious, to me at least, that the designers of D&D assumed that the number of combat rolls would be HUGE relative to the number of non-combat rulls. Many groups roleplay out-of-combat stuff more often than they roll for it, and you don't need to roll 8 Diplomacy checks for a single encounter -- it's an all-or-nothing on that first roll, with no retries available. Based on how it weights out, the designers appear to have decided that given how many in-combat bonuses the fighter was getting, he should get
nothing for out of combat. The assumption was apparently that people who wanted out-of-combat bonuses would multiclass.
Now, I'm not saying that this is true in every campaign. I'm saying that it's what the designers were using as their standard. My evidence for this is the totally lame-ass skill points and skill selection that the fighter gets, as reported by all of you on the other side.

This is, from what I can tell, the best possible theory for why the designers
totally shafted the fighter in everything that wasn't combat (assuming that "they are poop-heads" is a nonconstructive theory).
So, from that viewpoint, the question becomes, "Is your campaign balanced in that same way?" How many combat rolls relative to non-combat rolls do you have over the course of, say, a year of gaming?
(Note: "Time Spent" doesn't matter -- if you do three hours of roleplaying followed by one hour of combat, but you only roll the dice ten times during the first three hours and then roll the dice fifty times in the next hour of combat, your dice rolls are weighted heavily toward combat.)
If you're running dungeon hacks, or even combat-heavy adventuring that has roleplaying and mystery elements, it seems pretty clear that the number of combat rolls heavily outnumbers the number of non-combat rolls. If that is true, then your fighter is getting a ton of bonuses on his rolls compared to what the poor bard is getting -- sure, he's got great ranks in social stuff, but does he get to use his Diplomacy and Sense Motive more often than the fighter gets to make an attacK?
I'm sure, for some campaigns, that the answer is "Yes". I'm sure that there are some campaigns in which the ratio is
not so heavily weighted toward combat. In those campaigns, since the ratio no longer evens out -- the fighter's disadvantages now outweigh his advantages, since he's making fewer combat rolls relative to the number of other rolls out there -- the fighter is indeed weaker. In which case:
Why play a fighter here? It's obviously not the right PC class for this campaign. It's a great class for NPCs -- the grim and tactless guardsmen in the swashbuckling campaign, the grunting mercenaries in the dashing pirate campaign, and so forth -- and it should be left as it is, but it's no longer right for PCs. Or you could change it, but then you should also consider giving the wizard more spells and changing their spell list to include more social spells, giving the rogue more social class abilities to make up for their lack of Sneak Attack usage, giving the Paladin something to make up for his lack of ability to use Smiting, and so forth. The fighter is not the only class currently balanced by combat abilities. It's just the most prominent one, and the one who suffers most spectacularly if you run a non-combat-oriented campaign. Your choices are to overhaul the fighter and make tweaks to almost every other class that has Rogue attack progresison or better, or to simply declare the the fighter class is only good for multiclassing or NPCs in this campaign.
It would be
very interesting, to me at least, to see wat the actual numbers are after a year. Maybe next campaign I'll start something like that -- keeping track of how often everything is rolled.