Intellectual compatibility is what makes a connection truly desirable and rewarding
When a comment that reflects your way of thinking sparks a sub's interest and they go out of their way to understand your mind - following your multiple accounts, reading through your posts and then messaging you with their homework already done - that's so special. The way they are ready to start the most engaging conversation on topics you casually mentioned months ago (which interest them as well), discovering shared views on broad subjects, teasing each other's brains, finishing each other's thoughts, without even getting into nsfw talks at all...
This kind of mental chemistry might be one of the most arousing experiences possible, just two human minds unexpectedly clicking despite time, distance, age, language, life experience or any other barrier that turns irrelevant when the connection becomes real.