I take a slightly different view, first I'll say that Strfry has so far been the most lightweight thing I have ever hosted.

Seriously, I gave it 4 cores and 16GB of RAM because I wasn't sure what it needed. The CPU graph doesn't register any usage at all and RAM's under 1GB, shit's ridiculous.

The DB size is under 100MB after a month of running. I know my relay is small, but shit that's super light. For context, I hosted a Lemmy instance for a while and that shit was gobbling up ~10GB per day at one point.

Anyway, where I'm going with this is moderating individual notes does nothing to conserve resources. Relays do need to stay on top of spam trends, so for example if I notice another crypto bot bullshit that my current filter doesn't capture, I need to modify it so that it does. But deleting individual spam notes is more effort than it's worth.

I think what you describe will happen client side, and my hope is clients will retain the ability for users to choose what's right for them.