It is easier to limit how many spells a day a wizard can cast it dose not matter if you know 100 spells if you can only cast say six.
Which in 3.5 means that you have to be about second level - and not count cantrips.
The argument that there is a spell for everything is just plain nonsense in my book of course there is a magical fix for most things the reason they are in the game is to help parties that are lacking that skill. Take knock the spell that is usually used as an example. I in 30 years of playing have never once ever seen this spell abused in a way to stomp all over the rogue. The only time I have seen it used by mages is when the party does not have a rogue to open locks. A wizard who memorizes this spell gives up other better useful spells so why bother when you have a rogue who can pick locks all day long until the cow comes home.
I don't think I could better underline one of the core problems of the wizard. "A wizard who memorizes this spell gives up other better useful spells". But the rogue, naturally, can't do any of the better useful things a wizard can so he pitches in by picking locks and allowing the wizard fun toys. 4e Knock wins here - it takes a minute to cast when the rogue can have the lock open in seconds.
I have heard the argument why would a wizard not get a wand of knock because it is so much better than a rogue ability. If the game was real life and death then that would be true but we are playing a game and as much as I like a lot of realism in the game there are times to have self imposed limits. So a player taking knock and just stepping all over the rogue is being a dick. And the DM is letting him by not saying no and talking to him out of game.
The point is
the rogue should be better at picking locks than the wizard. That you have to impose metagame limits on very basic roleplaying just points to a problem with the system.
But having a spell like knock allows DMs to have locked doors when there is not a rogue in the party.
No rogue in the party has never stopped me either. If necessary the PCs can use a crow bar or even a battering ram. Picking locks merely allows
stealth and speed. An unpickable lock can still be forced. So the entire argument vanishes in a puff of smoke..
Then there is the argument that fighters just point pointy things at people and mages move mountains. Boo Hoo sorry but magic is supposed to be special and powerful and moving mountains seems rather epic level and epic level fighters can mow down most armies. If players want to move mountains then don't play a fighter.
"If you don't want to be special and powerful don't play a fighter." Right.
As for "An epic level fighter can mow down most armies", Giant in the Playground had a series of duels. Level 13 wizard vs Level 20 fighter. The wizard was seriously nerfed - no teleporting away, no prebuffing, no scrying. And the fighter did win one - but that had nothing to do with being a fighter rather than being a glorified commoner with three quarters of a million GP worth of equipment. The level 20 fighter wasn't a match for the level 13 wizard, despite the wealth.
And for an army? 1 arrow in 20 from the commoners is going to hit. Doing about d8 damage. 400 archers with light crossbows? That level 20 fighter is going down like Jacques Cousteau.
A fighter's job is to protect the squishy team members and go toe to toe with big bad ugly things. If you think fighters are unfun to play then make them fun give them more things to do but stop blaming the wizards and magic on that.
The squishiest team member
can protect himself. A high level wizard is a hell of a lot harder to kill than a high level fighter (who just gets punked by something against his will save). The fighter's schtick is waving a pointy bit of metal around. This can be fun. A big part of the wizard's schtick is making pointy bits of metal
irrelevant. This too can be fun. Unfortunately, put the two together and there are problems.
To put things another way, in the 1970s
Pong looked like a fun computer game. As computer games go, a high level fighter is still playing pong - the wizard, meanwhile, is carrying a smartphone loaded with games. Including pong (Tenser's Transformation) if the wizard can be bothered.