Of course, you can decide not to part of a HOA. Nobody is pointing a gun at your head forcing you to sign to buy and sign the covenant!!!! If the covenant gives the HOA the power to subsequently change the rules, then the purchaser doesn't have a right to whine later. He should have read it first. It is just like any other contract.
If you move into the community you are covered buy the HOA rules. Yes you can decide to buy somewhere else, but you can not decide to buy in an HOA community and then decide not to live by the association rules. For the most part the people who run these HOAs are Liberal little house nazis that want to run everybodies lives.