I concede that it’s a niche way of working. The purpose, at least for me, is to offer a helpful way to look at more than one note at a time while working.
I read what you said here and understand.
An alternative to sliding panes that I’ve found really helpful is in Roam Research. There you can shift-click on a block or link and it opens in the right-side pane (and you can open more than one).