Judo players can do arm bars and choke people to sleep. Brazilian Jiu Jitsu guys can throw people.
However, there seems to be a perception that neither of those things can happen; that the two sports don’t connect; and that you should train one or the other.
It may be controversial, but I think that Judo and BJJ are so similar that anyone wanting to excel at either would be silly not to cross train. The secret is to respect the heritage and traditions of both sports and they will thrive together.