I see what you mean, and having looked a bit more deeply today, it's clear that jj is very compatible.
However, my point is that having two ways of doing this within a team is already confusing. What if one person writes a "this is how we work" document on the wiki and mentions some git, and the next person rewrites it to jj? It's extra things to think about. It's like supporting developers from a team with both Windows and Linux (Debian, Arch, Ubuntu, etc). Teams do it, and it's all possible, but it was nice that at least everyone used git.
However, my point is that having two ways of doing this within a team is already confusing. What if one person writes a "this is how we work" document on the wiki and mentions some git, and the next person rewrites it to jj? It's extra things to think about. It's like supporting developers from a team with both Windows and Linux (Debian, Arch, Ubuntu, etc). Teams do it, and it's all possible, but it was nice that at least everyone used git.