This is more of an issue on how Nexon handles new monsters they make.
'Many years ago' there was nowhere near as much crap as there is now. About 9/10ths of the things are what's been added in the last year or so, which is recent considering the age of the game. This is just how Nexon will classify their monsters, and there's nothing much that database websites can do about it - you could hand-pick them out but that will take a long time and would be a bother again when Nexon decides to add in more strange monsters every 2 months.
Nexon should have added more classifications like "Event" and "PQ", because right now they use the classification "Boss" as "everything-that-isn't-normal-monsters".
One suggestion could be for HS go back to the pagination system instead of the never-ending scroll system to prevent having to scroll so much, though.