Because it’s not something people commonly do. Because the GPG authors wanted to design for and encourage what they consider appropriate use and discourage and make difficult (but not impossible) what they consider inappropriate use. Removing a footgun for people not fully understanding the trust model of PGP or just slipping up doing that and then ending up in situations they didn’t account for. In general I could have a lot of criticism of the UI/UX of GPG but in this case I can see where they’re coming from and find this thread supporting it as working as intended so far.
That you need to have deep knowledge of obscure GPG internals to pull this off is by design. It’s not considered part of intended use. Similar thinking to why in Chromium you don’t have a button to bypass HSTS validation error but need to type in the cheat code “thisisunsafe”. It nudges users to stop and think more consciously about what’s going on.








DM me if you’d like to discuss further consulting on this project. I do think I could help you. However, reaching a proper design for this that is actually appropriate for your situation is non-trivial, goes beyond the scope of lemmy thread and would likely be paid.
I would also like these things to be easier and just be able to point you to something existing but the reality is they currently aren’t and such solution isn’t. But if you do push ahead and are open to sharing (potential security tradeoffs there too), maybe you’re in a position to be part of improving that situation.