Yes, I would argue against „one template per folder“, maybe for fast typing one mechanism to encode creating note from different templates in name of note, the template could be store in specific folder;
This behaviour could be implemented as separate plugin too
for example
[[My diary%%note_diary]]
will create note My diary.md following the note_diary template.
The syntax could be different, like typing == or any specific not so often used combination of characters, the characters could be even not allowed in note names so Obsian will then know that the action on the note is required and this is not the part of the note name