It is definitely possible, just with a more complicated (and slow) parser than what browsers use now – there's been some discussion in this thread.

As for whether it's necessary – eh, it's neat and might be useful sometimes but it's not a big deal I think. Personally, I remember a couple instances when I needed to override a few properties depending on context and it would be helpful, but `&:hover` is so much more useful.

Right and now that we have (or will, soon enough) `:has`, I really don't think it's worth mucking up the potentially very simple and sweet nesting syntax to support something that's probably usually a bad practice anyways (though obviously I'm speaking from a place of little experience using this)