At the property values referenced in above post, the opposition to apartment buildings is not exactly about properties’ sale prices. Presumably, the residents are happy where they live, so their priority is not in maximizing the sale price, but keeping the riff raff out that cannot afford $1M+ homes, and hence have to live in apartments.
The concern about decrease in home prices is just cover from accusations of discrimination, although keeping home prices high is a necessary component. But maximizing them is not.