I'm not entirely sure why the solution to the tracking problem isn't seen as simply scoping cookies to the domain of the top level page. I'm dubious that there'

I'm not entirely sure why the solution to the tracking problem isn't seen as simply scoping cookies to the domain of the top level page. I'm dubious that there's any value to cross site cookies that isn't in service of tracking, since oauth-style flows provide a better and more open mechanism for providing cross- or multi-site login mechanisms anyways. Is there some value I'm missing? Why blacklist this? I'd rather whitelist it.