Re: the garish house, etc.
That kind of aesthetic can and does affect resale values. In addition, without done kind of external (city, HOA, etc.) rules regarding decorative aesthetics, materials & horticultural decisions, you could have homes with truly objectionable or even dangerous features, such as unmarked toxic plants (see Alnwick Garden) or pornographic/violent vinyl siding or wall wraps.
I know in our current neighborhood, all of the initial corporate homebuilders had limitations on which materials (type and color palette) they could use for external walls and fencing based on contractual agreements with the original landholder. So when we built our house here, certain brick colors were not available.
Some, but not all of those limitations are still enforceable.