So there's a lot of DHT network scanning going on for sure.

There is an entire category of free software whose purpose is to create an index of the DHT network. :) The idea is to allow users to find and search for torrents in a completely decentralised manner (i.e. without relying on any centralised trackers or search engines).[1] A good example is bitmagnet[0].

[0] https://bitmagnet.io/

[1] With the added benefit of greater resilience, as centralised "chokepoints" are often the primary and only targets of takedowns.