> And people enter them willingly? Can someone explain why?

For some, the house they want happens to be in an HOA neighborhood, so they oblige. For others, they like the "order" that the HOA demands of the homeowners that live in that zone - grass and roofs and paints are all "approved" which definitely provides some semblance of consistency.

In my experience, HOAs are exactly like this article describes. People that like power for power's sake becoming anal about the people they have control over, under the guise of "consistency" and "order".