Are you referring to the fact that pip appears to build such dependencies twice? Because if so, then again, we’ve already agreed that having pip reuse cached wheels here would be useful. And even if pip doesn’t do that at the moment, there’s a difference between “cannot install via wheels” and “is extremely slow due to building dependencies twice”.
If you’re referring to something different, then you’ve not managed to express the problem clearly yet, because even across about 3 different long threads, people are still not clear what it is that you’re insisting is currently “not quite possible” 