Overkill imo. Could be a new feat, similar to "only the ones who I follow can reply" it would be nice to have but for spam like replyguy it would be tideous to zap every note. Paid or whitelisting relays are the solution imo, pay once and that's it, minimal to no spam in the relay.
Your client could auto-zap it when replying if you have a built in ecash wallet or NWC set up. @keychat charges you 1 sat to send a DM and it seems to work great. I’ve only sent a couple messages though. If you only read from paid relays, you’ll miss out on all the notes from people that can’t afford to pay for the relay. Paying 1 sat to post a reply is much more manageable than paying 50k sats upfront for a relay.
Doesn't need to be 50k to prevent spam even 5k sats would probably be enough, a spammer could spend 50k or even more to spam in a single relay, but then all the bots would be banned after a short time and he would have to spend again. I would see a zap to reply as a way to prevent troll comments and I think it would be a cool feat, as long as we have options we will use them the best way.
I just threw out 50k cause that’s how much I thought nostr.wine was. I just checked and current price is 18,888. I’ve happily paid for nostr.wine, but I still read from free relays cause I know many people can’t afford to pay for nostr.wine and I still want to read their notes.