The most generous hypothesis would be that Planetscale is an increasing popular product among the HN crowd - specifically, those who have to maintain large MySQL deployments. It seems like a very good product that is seeing something like viral adoption across those companies.

The next ingredient would be if dropping MySQL tables is a relatively big pain (or known but unmanaged risk) that most of those people have experienced at some point.

Then this feature would be exciting news for that not-so-small cohort and that seems sufficient for HN upvotes?

I don't know if that's what happened today. I've heard about planetscale a few times but never used it. I can attest that dropping tables is always scary.