Thunderbirdreally needs Categories, some simple pre-sorting of email types into manageable buckets.
I rely heavily on the Gmail Category tabs; in Promotions, Alerts or Forums I typically only need to read the subject lines, so I Select All, maybe uncheck one or two, and click delete. This also reduces mailing list noise in my inbox tab making important things easy to notice.
It would be possible, but very tedious to teach tag filters. The beauty of the Gmail case is it is self-learning. Anything classed wrong is simply dragged and dropped or menu selected to a new home.
If this was in Thunderbird, I could switch in a moment! I expect it's non trivial but I wonder if this might be implemented using a very simple Markov chain, like the early spam filters, so it could refine its decisions over time.