I did my research years ago when I enabled that config option. Meanwhile I used various sandboxing tools like flatpak, firejail, apparmor or whatever and there were no issues so snap is special case in this regard (I really think this should be fixed in snap). The problem is that when I did research about snaps I found nothing.
This being a corner case also means it’s hard to figure out. I spent few hours talking to snap devs until this idea occurred to me. Next time someone may fill a bug which won’t be resolved for days, months or even never.
Documenting such cases in form of checklist or “common errors” would prevent knowledge to be forgotten. Even if users won’t do a research themselves it will be easier for devs to ask right questions instead of trying to solve each puzzle from scratch.