One mistake that I frequently see newcomers making is starting the same discussion in multiple places, which goes against w:WP:TALKFORK. This creates a lot of messiness: it uses up editor time because folks type out comments others have already given elsewhere, makes it harder to keep track of things, requires work to reconcile differing outcomes, can be seen as inappropriate canvassing/forum shopping, etc.
It occurs to me that the new discussion tool might be able to help address this issue by identifying possible discussion forks as they happen. The trigger for this would be if a non-extended confirmed editor starts writing a new topic that has the same header as a topic they recently (say, within 31 hours) started at a different page. (A more advanced version could parse the content as well, looking for, say, > 90% similarity.) When that condition is met, it would trigger an editnotice that would say something like Please do not start the same discussion in multiple places. To draw attention to a centralized discussion, use the Please see template to leave an invitation.
Would it be possible to develop this feature, @ESanders (WMF)/@PPelberg (WMF)? (This might also be considered a possible implementation of Edit check.)