Not doing this is wasting a bit of signal, probably a fair bit of it. Making the spam-tracking data global, so all sites contribute to and benefit from it brought a huge benefit, and I can't negate that.
However, I have some rather big reservations about doing this, because how folks review can be distinctly different from site to site. Each site has a slightly different style of moderation, both from the community and the elected or appointed mods. This means, it's easy to be great at reviewing on site A while often finding yourself at odds with decisions the community has made in the past on site B. Review audits are ... well known to point this out. Put more simply, 'known good' and 'known bad' can differ vastly between any two given sites and is quite subjective to begin with.
This also moves us into a new level of precedence when it comes to how your behavior on site A can affect your ability to use site B. Currently, there are only two cases where this happens:
- You are suspended by someone with a very high level of access across the network, reserved only for extremely exceptional cases
- You originate from a network that our spam system has been tracking, and it slows you down or prevents you from posting (not exactly behavioral, if you weren't the one being a jerk)
I don't know if I want to cross the path of having site-level restrictions follow you around, despite how incredibly convenient it would be for us.
I'm not putting a status on this yet, but as proposed, it's not likely to be implemented. What remains is if you really screw up, on several sites then .. that's a bit more pathological and .. well, I have to think about it.