I've played in games that don't allow multiclassing, but never games that don't allow feats. Go figure.
Anyway, odd nomenclature aside, in our group it was a group decision. I didn't outright decide "No Feats". As I said, we tried them. Probably for close to a year or so. I've written about this in other threads so I'll not rehash it all here. The bottom line of it all was simply that we felt Feats took away from creating unique characters, which was the opposite effect that the designers were going for I think. After all the trials, WE decided we didn't want Feats in our games.
In short, it's not "just DM's" that don't want Feats in their games. Some players don't like them either.
I ADORE players like you. Three 9's? Hope you like failing skill checks and saving throws regularly. Because, guaranteed, I'm going to beat you like a pinata for that choice. Makes challenging the character ridiculously easy. Oh, you dumped statted Wis? Fantastic, every exploration pillar segment sees you riding the pines and you're guaranteed to see hold person spells coming your way. Makes DMing so easy when you gift wrap characters like that.
Personally, I think I'll go with JC's explanation. Most players play to concept, rather than mechanics, and choose to make their characters without trying to min/max their way into some sort of one trick pony. Or, perhaps, their DM's aren't softballing the campaigns and making every encounter perfectly tailored to the PC's strengths and those other stats that you "don't care about" come up regularly.
The idea that it's "foolish" to play standard humans is hillarious. Hrm, players are making characters with giant holes in their competency? FAN-FREAKING-TASTIC.
Why is it a group decision about whether or not my PC can choose a feat? Does the group decide what spells I'm allowed to choose? What weapons? What background?
What business is it of 'the group' to decide things about my PC?
Each player gets to decide these things for their own PC.
"Sorry mate. We know you wanted to play a fighter using a short sword, but we all voted and we decided that we don't want short swords in our games."
"Sorry mate. We know that you want the Actor feat, but we all voted and decided that feats take away from creating unique characters, so you'll just have to take +2 Cha like every other bard!"
WTF?
Yet it is you, as DM, that allows/encourages players to veto feats, but not spells or classes or weapons. You are responsible for this!
If a player came to your table and wanted a feat, you would tell him that he can't because the rest of the group think that whatever feat that may be that the very act of choosing it will make his PC less unique? You are giving the group veto power over feats, but not other game elements?
No, it's you. If it were not you, then you would rule that each player gets to choose whether or not to take a feat, just like they choose everything else about their own PC. The players that want feats can choose them, the players that don't want them don't have to choose them. That's democracy!
Or...
"Sorry, we know you wanted to play a Jedi, but we're playing D&D."
Feats are an optional module. They should not be assumed to be in the game.
My table doesn't use multiclassing and doesn't use all of the feats. A player can't just decide that they're going to do that.
Why is it a group decision about whether or not my PC can choose a feat?
Paint the picture however you like, with whatever sketchy data you like, but the people that drive the D&D market are the people that explore all their options. I've played with about 8 different distinct groups of players in 5E era (excluding single session delve groups) and:
1.) They all made use of the feat rules.
2.) Humans were only slightly more common than other races - and every single human character was a variant human.
I'd love to look at D&D Beyond data that shows:
1.) Only characters that have been in the system for 4 months, and
2.) Have been updated in level twice since being put into the system.
That would give us an interesting view of characters that are likely in play...
Assuming you disagree, why does your logic not apply to other optional rules in the game? There is an optional rule to have short rests be only 5 minutes instead of 1 hour, and an optional rule for Facing rules as well. Why are you not arguing each PC gets the choice to use those optional rules?
And to make it clear feats are optional it says right in the Player's Handbook, "But this chapter is for players who - with the DM’s permission — want to go a step further. This chapter defines two optional sets of rules...Your DM decides whether these options are available in a campaign."