Generally yeah, but the value of it dives of the cliff in some cases, compared to the hassle it introduces. Lets say you create a encrypted LUKS partition with a 32 character password. Would it be more secure by nesting 3 more encrypted LUKS partitions inside of that one, with each having different 32 character passwords? Yeah sure, but you're already pretty secure with just one as long as the password is good.

In the case I mentioned, adding TLS certificates to something that is already signed in a similar way that TLS would do, would add nothing in terms of security, but would add additional privacy.

I see your point, and I repeat I'm not arguing with you, I don't have the knowledge you clearly do, but onion layer security is I guess useful when mistakes are made -

> Lets say you create a encrypted LUKS partition with a 32 character password. Would it be [...]

Quite so, but if someone does a booboo and uses a 3 character password for one of them (well, imagine more sophisticated form of such a mistake) then the extra layers become valuable.

I guess it's about guarding against dumbness or accidents rather than correctly implemented best practice.