Why we should use a GPG key?

I work in a company that uses gitlab but nobody use a gpg key or ssh key with their account.
I’m trying to convince them that using a gpg key is a best practice but i could not answer why when they asked me, could you please give me some good reasons?

I know that having a verified activity on gitlab is a good information that we are the one that committed those activities… but again they keep asking me why and i don’t not know what to say.

In this company we are several dev who work with differents computer of the company everyday, in that case is it worth to use a gpg key?