Being a paying customer myself I think Notion also appeals a lot to an audience that likes to feel productive and self optimizing while just procrastinating the s*t out of their day (and I am sometimes guilty of that more often than I would like).

This audience has a tendency to jump towards productivity and optimization hscks/shortcuts. And a lot of these products/templates promise exactly that.

So Notion in regard to this specific target audience is a great signal for others to identify an audience ripe for milking. It makes for good marketing and audience self selection.