Some discussion in these two threads:
My personal thought is that hovering probably makes you weaker tbh, since when I hold the mouse over a space I’m prone to going autopilot and playing too fast. I think letting the mouse go and staring at the blank board forces me to make better choices.
I think it’s also probably overall helpful for streams even if you dislike it–waving the stones around is a primary way to communicate which stones you’re considering, and I’d probably practice doing it more actively if I was streaming. (I know some streamers prefer to play custom games with analysis mode on, so they can play out a quick variation to explain something to chat.)
That said, I don’t think a “hover stone opacity” slider would be particularly difficult to implement. You could probably do it with a CSS tweak too, tbh.