I did not, however, realise that "customized comment pages" was a thing, much less a problem for folks. I'm so accustomed to encountering them and then just appending &style=mine or using the header-bar option for that, it didn't occur to me. But I've just encountered a discussion (via rec from astridv — thanks!) in which some folks said they simply won't read fics that open in customized comment pages.
So I've disabled them for my journal. I find the resulting default view blah and unpretty, but my custom journal view is a little bold for fics (dark blue borders! bright white text fields!), so a lot of that is simply the contrast.
I do apologize to anyone who disliked the former method.
And I'll still be crossposting everything to DW and AO3 anyway, so it may not really matter, but what the heck. Alienating readers is profoundly counterproductive and never my intent.