I personally find this annoying. I usually like to keep one pristine and always current working copy of main (and develop if applicable) around for search and other analysis tasks[1]. Worktrees would be ideal and efficient but due to the mentioned restriction I have to either waste space for a separate clone or do some ugly workarounds to keep the worktree on the branch while not keeping it on the branch.
jujutsu workspace are much nicer in that regard.
[1] I know there are tons of ways search and analyze in git but over the years I found a pristine working copy to be the most versatile solution.
Also, if you end up relying on it for space reasons, worth knowing that cloning from a file:// url switches the hardlink mechanism off so you end up with a full duplicate again.