Honestly, I think it depends on the situation. An upvote definitely shows you saw and appreciated something, but it doesn't really start a conversation.
If someone leaves a thoughtful comment or asks a question, just getting an upvote can feel a bit... dismissive? Like you couldn't be bothered to actually engage. But for quick "nice post" type comments, an upvote is probably fine.
The thing is, people comment because they want some kind of interaction. Even a short "thanks!" or "good point" makes them feel heard in a way that just an upvote doesn't.
That said, I get it, replying to everything can be exhausting, especially if you get a lot of comments. Maybe pick the ones that seem like they actually want a conversation?
The "blah-blah-blaaa" comment is kinda harsh though. Quality over quantity for sure, but some acknowledgment goes a long way.