Sometimes I wonder if the notion of finding a place where people "share similar areas of knowledge and opinion" is the problem. Classical communities were made up of a plethora of types, the only implied shared interest being their own livelihood. As a programmer I think I feel lonelier with other programmers than I do in a random group of people. If you are in a community that has gathered around an interest (rather than a place), there is essentially only room for that thing. Anything else would be OT.

More general philosophical or otherwise broad topics might give a little breathing room but imo not enough. Irl to be a close friend, I find someone has to be as willing to talk about what they ate for dinner the night before as what they think the point of the universe is, and everything in-between. That's how trust, empathy, understanding, and ultimately a stronger bond is built. Coming into a place with people of similar ideas will superficially feel good, you get that reinforcement and validation of your ideas, but this pales in comparison with genuine human community.

I don't really have firm ideas or solutions. Finding a really good community, whether irl or online or whatever is one of my life goals though. I believe I'm still in the part of the journey where I need to define and learn what that even means, before I can find/join/build/etc one.