Proof of work!
No response...they didn't see anything or it wasn't worth their time
Like....worth at least an acknowledgement and reading enough to react in a positive manner
Zap....worthy enough to express approval with sats
Boost/renote....stamp of approval
Reply/Quote....and investment in the content and a desire to add to it or engage in conversation. Spending the most valuable of all resources, time.
All engagement is useful for feedback, some is much richer data. I don't want to deprive myself or anybody else of any of it.
One thing is for sure, 1 like on Nostr is worth more to me than a like elsewhere.