I don't really know. There are guidelines and promoting those guidelines to new users can be beneficial. I do sometimes comment on changesets by other users where this happened with the use of normal editing tools (iD, JOSM) where some more care can really be taken (JOSM even warns about large changeset boundaries). But I try to phrase it as a friendly reminder, not so much a broken rule.

Some things like reverting vandalism or fixing large geometries like coastlines or motorways often make large edits necessary anyway. And often it just happens by accident. I have added some cleanup changes to the wrong changeset more than once and then got a changeset for a whole continent. The immediately visible history on the OSM site soon ceases to show that changeset and another will take its place, so personally I don't see much of a problem to get worked up about.

So my stance is basically: It happens, we can't really prevent it anyway (although I'd love a spatial auto-split in StreetComplete and JOSM – Every Door has it, I think), and as long as the norm is that people try to make smaller changesets, I guess we can live with that.