Do NOT automatically delete materials with no user
I'm not sure why anything would be automatically deleted. This is unintuitive, has caused pain for so many people, and is just a bad idea. I really can't believe this is a thing in version 4 of this software. I'm guessing it's still in version 5 too.
3 Comments
It's just how blender's data blocks work (not only materials). You can always set a fake user on a data block to prevent automatic deletion.
If blender didn't automatically delete data blocks with no users, lots of blender files would be loaded with unused data, and that would be a reason why blender automatically deletes unused data when you change files, simply because it's unused.
there is always the possibility to manually clean up the file...
Yes, but to me it seems easier to just set fake user for data blocks that shouldn't be deleted. Also there is enough of a warning with the zero users indicator in the data block lists, and it only deletes data blocks with no users when the file is closed, so there shouldn't be any problem for anyone who remembers to set fake user if necessary.