Maybe not, but it could at least help fund relays that may otherwise go offline due to the extra cost of spam. There's a similar advantage to all the one sat spam transactions I get on Lightning. Sure, it sucks, but at least fees are being paid and even I'm getting wealthier by some micro amount. That's certainly better than getting absolutely nothing from spam like now. It would also be cool if users could set a fee for interacting on their notes. I doubt anyone who can't afford a few sats are or whatever the amount is are going to say anything I really care about anyway. It's probably just going to distract me and add no value.
Discussion
Pay me to comment on my note could be interesting. It changes how people interact with the network though. For some it would be a wash, put 100 sats in a pass them around forever. Big accounts get paid. Small accounts have to pay to be here or get bumped down to lurkers.
This goes beyond just spam though. I'm almost definitely not going to get any value from someone who can't or won't spend whatever small sat amount is required to interact with me. I don't even necessarily need to get the sats if there's some technical way to give it to my relays instead. I'd prefer to make it optional though if possible. I just don't really need to see shit from low value npubs. And if I do see them there should at least be a cost for it if they're being sinister like spammers. The free for all model clearly isn't cutting it regardless.
Obviously, you could just have a client hide notifications or whatever from people you don't follow, but that doesn't help with the cost of the spam and low value responses.