"Objective reality" is only the source for the least interesting truth. The truths that really get people fighting over concern best courses of action, moral matters, aesthetic issues, and things like that, where there isn't some singular objective truth (and even if there was, nobody has access to it).
You say that, but some people really do give you a hard time if you try to assert that there is one, definite, objective reality.
> thinks like that
These aren’t truths. It’s cases like “is the earth flat?” that have an answer in objective reality and people still argue about it where some people are simply wrong.