Do you honestly believe that it's efficient game design, to track advancement of a stat that can't actually be represented using the basic system mechanics? That it's worth tracking the wizard's attack bonus all the way up to +12, when a +12 can't meaningfully interact with the AC 35 enemies that the high-level wizard is facing, such that they need a 20 in order to hit regardless of their level?
First, please ease off on the outrage. I'm not your enemy.
So first, what part of a Wizard's BAB can't be represented in the system mechanics? Or were you referring to something else?
Second, a +12 BAB can be very useful. You just have to apply it to Touch Attack (ranged or otherwise) spells.
As for levels: They don't exist in the real world. A chess grand master is just as hittable and breakable as the novice. No increase in hit points or AC, no matter how far they advance their chess skills.
But I'm still confused. You keep saying that I don't like, or shouldn't like class and level systems, and I don't know where that's coming from. I like them just fine.
But you're focused on levels, and I like to remember the "class" part: Each class has its strengths and weaknesses, and that's how it should be. The tough characters should get tougher, the quick characters should get quicker, the sneaky characters should get sneakier, spell casters should be able to cast better spells, etc.
The universal proficiency approach says the quick guys get tougher just as fast as the tough guys, and they get sneakier just as fast as the sneaky ones do. Universal Proficiency systems make it very difficult to improve your specialty at anything other than that generic rate. I can get better at something just as fast as the specialist, and never waste a moment on practice.
Like I said though, I'm not saying that you're "wrong" about what you like, or why. I'm just saying that other people can legitimately disagree with you, and they're not "wrong" either.
Small tangent: I knew a gamer who always played Wizards, and almost always Elves. Characters died at a regular, steady pace. Because the character was proficient with a long sword, this player thought that made them a minor fighter. So at low levels the combat sequence went like this:
Round 1 - Cast Mage Armor of Shield if MA was already up.
Round 2 - Cast Magic Missile at the Orc (or whatever they face)
Round 3 - Having exhausted low level spells, the character would draw her sword and charge into combat.
Round 4 - Die.
At first level, in D&D 3.5, the Wizard's attack bonus (not counting ability scores) is only one less than the Fighter or Barbarian. But even with a good AC (Mage Armor + Shield + Dex can get you a 20 at 1st level), the character isn't going to hit well or often, and doesn't have the hit points to stand in combat.
End Tangent
That was an example of a player who understood what their level was, but didn't really grasp the difference in the class specialties. The player was real and the situation I described happened every two weeks or so. The player had some developmental issues, and those limitations made it hard to learn from past mistakes, so I'm not getting down on them. I just included the tale to emphasize that character class should matter just as much as levels do.