That was my first house. There was an HOA, but antenna restrictions never came up, even when I put up a 5/8 wave 10m vertical and an inverted vee. There were many TV antennas scattered around the neighborhood, so I figured if there were any restrictions, they weren't being enforced. Nobody ever came to the door telling me I had to take any of it down.
Caveat Emptor. It's no one's fault but your own for not doing proper research. Maybe next time, you'll pay attention.In some cases, the person didn't read the fine print, or it wasn't disclosed.
There might be grounds for taking that to court, but IANAL.In some cases, the restrictions didn't exist or weren't as severe at the time the home was purchased, but were imposed on the homeowners by the HOA after they took possesion. Or the rules weren't being strictly enforced then, but are now. Or the HOA has made the new rules retroactive and won't recognize grandfathering.
This is the most likely, IMHO.And in most cases, the person didn't think the rules applied to them. Or didn't pay any attention to them in the first place.