696848204c
STL/PLY (also Collada) use `BKE_mesh_assign_object` to assign a mesh (already in main, has a usercount of 1) to a fresh object. That function does a bunch of (unneeded) things (test modifiers/ materials which is not necessary since these are fresh objects) next to increasing usercount. Collada steers against this by reducing usercount again. Other importers such as alembic assign the mesh directly to object data (which is also what this PR proposes). Pull Request: https://projects.blender.org/blender/blender/pulls/123558