Questions tagged wordpress.com are off-topic, but people regularly miss-tag their questions believing it's a WordPress question therefore wordpress.com, not realising wordpress.com is a hosted service.
I think it would be good to revisit this in a few months to see if this has had the desired effect of changing behaviour. If not I believe the dual tag approach suggested in the comments is a good avenue to explore for follow ups
wordpress.comtags would be considered off-topic anyways, why not just name it
wordpress.com-hostingso there's only one tag? It's not like the free or premium would be handled differently than each other.