What is the purpose of cross-play?

I know that it's been a topic of discussion, prior to the release of NHL 23, but what is the actual purpose of it? Meaning, if gamers from two consoles can play with and against each other, why aren't the EASHL 6v6 lobbies full?

Although the above question may or may not be rhetorical, does the state of the current iteration of the NHL video game series warrant the tag teaming? From my point of view, and with first hands (on my PS5 controller) experience, and viewing/reading the numerous issues with NHL 23, my $94 CAD could have been put to better use.