Yeah, if you block someone (not ban them) they can still go to a community you moderate and post there - but you won’t see it. Obviously that’s not ideal from a moderator perspective. I tried just using one account and not blocking people, but there are a lot of trolls/arseholes/bots out there and I just don’t want to see their drivel on my feed - even if what they say isn’t technically against the rules, or doesn’t met the criteria to earn them a ban. And you can’t ban accounts just because you don’t like them (or you can, but that’s not good moderating).
Also moderator decisions are meant to be made objectively and I find having two accounts helpful to maintain that objectivity. A comment from my mod account is official but a comment from my browsing account only carries the same weight as a comment from any other user. Some iOS apps allow you to distinguish moderator comments from your standard comments. That works great but it doesn’t seem to be the standard across all platforms/apps.
I’m not a volcanologist or anything, but surely you were taught there are different types of eruptions at school? The Pompeii one was some kind of super heated gas and ash cloud (again, not a volcanologist) that people had no chance of outrunning. The Icelandic one that shut airports blasted ash crazy high into the atmosphere, caused tonnes of disruption but not too much destruction. This one is a slow boiler - they had lots of advance warning, no toxic gas, no giant ash cloud - just a slow moving lava flow that is still causing destruction but hopefully no death.