I have a close friendship with a solo F on here, she gets a lot of messages and she often shares with me for a laugh.
We were chatting about this the other night and have summarised that
10% of messages would be of interest so it might mean further conversation.
10% are so dumb they warrant a dumb reply. Just because they are from idiots.
the remaining 80% are the run of the mill boring and probably a copy and paste. Why would you bother wasting your time replying to rubbish.
Maybe the site should provide a Reply Template button where you can hit a button and acknowledge the message with a customised reply like
"Hi
You've had a response from your recent message.
Unfortunately on this occasion the recipient has politely declined. Thank you for your interest. "
Also as a solo M profile user myself I do read profiles and only message if there is a realistic chance that it's going to go further otherwise chances are you just viewed as another pest.