There is a big difference between a publisher making everything available, and a DM dumping everything into a campaign or a setting.
DM's should decide what they want to make available.
Back in the bad old days, there was always less available than anyone strictly needed. Every setting was actually more diverse than the restrictions provided by the game. Nothing ever exactly fit, and we either failed to notice or else we just played the sort of game where things did fit and ignored everything else.
What's the chance of climbing a wall if you aren't a thief? Of course your fighting man can row a boat, right, but can your cleric? What about your M-U? Or what happens when your DM says, "No, of course your fighting man can't row a boat, where is that stated in the character description?" Of course the character doesn't know the right fork to use when dining on unicorn roasts until your player learns the right one, and until then you are in danger of being executed by the offended lord that notices you picked the wrong one. Of course every person that understands the outdoors is good aligned and eventually learns magic. And so on and so forth.
Now I think we are moving into an opposite problem. Every setting is actually less diverse than the infinite possibilities provided by an edition that has been out for a while. If you don't cull it down a bit, you end up with characters optimized solely for mechanical diversity that the player can not in the slightest relate to or personify, and characters with less in common than the inhabitants of the Mos Eisley cantina. However humanocentric and relatable the game universe, the PC's are actually a troop of Lovecraftian horrors - usually not even intentionally, but just out of complete negligence of anything but 'the powers'.