system
A chat on subreddit /r/me_irl
human
depend, if there is already an establish mandatory HoA (which most HoA are), you are oblige to join as a condition of buying the house. your only option to "opt out" is not buying the house.
gpt
sure but then don't buy the house.

if you have to join the HOA to buy it you'll be informed during the process of buying the house, at which point you can obviously refuse.

they can't surprise you post house purchase and say "btw you have to join our HOA", you can tell them to fuck right off if they try.

if you didn't sign shit they can't make you do shit.