It's interesting how many people in this thread are defending the decision for D&D4 to fix the problem. Yet no one is questioning or attacking that decision or D&D4.
Many people are saying the problem exists, but so far there's been very little examples of it in play.
For the record: I'm not saying the problem did not exist. Nor am I saying that D&D4 did not fix it. In fact, for me D&D4 (right or wrong, good or bad, fixed it or not) is completely irrelevant in this discussion.
Can someone give examples of the subject (not theories on or defense of the issue)?
Several examples HAVE been given. Fighters are easy to lock down, and lack the ability to lock other things down (and when they do, its frequently decried as "cheese", see any spiked chain thread). They have to dump a load of cash into duiplicating spells in order to function, and that's assuming the DM either awards the necessary gear or doesnt throw a fit over players buying/creating magic items. Their poor will saves and low mobility are a hinderance in combat, when the game moved to require a full round action to get a full attack. There are a myriad of ways to negate AoO's (tumble, withdraw, etc), which arent overly lethal and frequently a better option that awaiting the full attack the following round. Spellcasting became considerably more difficult for a fighter to disrupt in 3rd edition with the remova of segment based cast time.
And that's just combat. You can build a character that does gobs of damage (lancer for example), but its not readily apparent to many players and relies on material outside of the PBH. One of the classes that was considered the most basic requires a lot of planning to function well.
Outside of combat, where a significant portion of my games take place, fighters are even worse off from their character abilities. They have a god awful skill list and 2 piddly skill points per level. Contrast this to wizards, who I feel, make more of an impact in fights, and can easily rule non combat encounters with a vast array of spells. Hell, most things a wizard can summon have more non-combat utility than the fighter.
You'll note I included the phrase "character abilities". I've seen many times someone pipe up that their fighter was the tactical leader of the group or the party spokesperson (apparently ignoring social skills). If the same fighter player was playing a caster, he could come up with the exact same plans and give the exact same speeches. Stuff you add to the fighter outside the scope of the rules can also be added to a caster character that has more rules based options.
You'll hopefully forgive me if I dont list each and every time the mage in our current game uses said spells in the way they were intended. If you havent seen it, you're playing with blinders, low level or your wizards are being lazy and/or stupid. I dont think enumerating times where detect thoughts, charm person, phantasmal force, gaseous form (and that's low level stuff) etc came into play will change your mind.