AGI may initially reduce the incidents of SEO spam, but I very much doubt that it can eliminate it. The same can be said for human vetting. The thing to keep in mind is that SEO is performed for different reasons and takes many forms, so developing a universal model will likely be impossible. When the current forms of SEO spam become less effective, more effective forms will be adopted. Any form of filtering also presents the problem of false positives. More aggressive filters would likely produce more false positives.
Blacklists are also problematic. I have an email account with a smaller provider that I never bother to use since there is a good chance that their servers are blacklisted at any given point in time. Getting their server removed from these lists is non-trivial in most cases. Once they are removed, they usually get relisted within a few months. The problem also runs in the opposite direction: I have corporate email accounts where every external email (including those from certain departments of their own organization) is labelled as such and as potentially suspicious simply because blacklists are not sufficient. The only reliable outcome of blacklisting is the reduced reliability of communications channels.
User reported abuse is even more problematic since it opens up avenues for abuse. While it may be relatively easy to filter out bad reports in situations where there is a minimal vested interest (e.g. finding something disagreeable), that won't be the case when there is a considerable vested interest (e.g. attacking the competition).