I don't really get how tbh. Isn't Option 3 the exact same thing as Sass except the "&" is required in a few more places than it is in Sass? It's also optional in Sass so I already write that way (always using the "&") personally
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)
I never use & when I am only nesting. So when I am skimming code quickly and I see an & I immediately know there is something else happening besides a nesting, for example &:hover.
This is probably something I can unlearn but until then it is very jarring to see & everywhere.