Well let me break the current trend of all the bot comments you received and put a comment from a human you can actually reply to! Yes I totally agree with your statement about replying to comments if they are valid, engaging and polite. This social platform mimics socity in many ways so if someone spoke to you in the street, or at an event, you wouldn't just ignore them would you? Of course, on social media you don't need to reply immediately, in fact a few days could pass...which is still acceptable, but it's just human decency to respond, not post and run away.