RPGMemes

And the DM immediately shuts that down by telling you that a horse or other creature doesn't have the appropriate anatomy to be a mount for a centaur

You'll still max out the carrying capacity of the bottom centaur after stacking only 3, maybe 4 with max STR or a Belt of Giant Strength. Now if you throw some castings of Levitate into the mix...

if centaurs are common i'd have to think about centaur compatible cities, houses, baths and what not, and tbh my cities, houses baths and whatnots are barely human compatible.

if they are super rare you'd constantly be left behind outsides of buildings because you dont fit on a spiral staircase or you've got thrown out of the tavern because your clopping annoyed the other guests, hell evey npc interaction would probably involve explaining the strange horse dude to someone. nope no centaurs, we can compromise on satyrs, teacup minotaurs or inverted merefolk. two legs maximum, sorry.

By asking to play a centaur, you're either declaring that your character will be constantly naked from the waist down, or opening the can of worms that is "what would centaur pants even look like?"

They're worried you'll constantly make puns about women riding you.