What if the DM is new too. No one will know about any other to play, because the new books only give one choice as an example. It allows options but shows you none.
Then that comes down to just differing philosophical preferences.
I myself do not feel the need to help players who "just don't know any better". If the DM doesn't know of alternative ways of playing and the players do not know of alternative ways of playing, then they most likely will just play as the game is written. And I do not have an issue with that or find that to be a problem. The game works fine for new players. They can make do.
And I feel this way mainly because if this DM and table players decide at some point that they want something different than what is in the DMG... they can just go looking for alternatives themselves out there in Google Search Gameland and find many different possibilities, rather than rely on a singular variant rule they might get from the DMG had WotC printed any.
That's really my thing-- alternative rules in a DMG are going to be just as useless to a predominant number of tables as the new rule is going to be. So with the exception of that small handful of tables who might like that one alternative variant rule WotC could have included... most tables are going to end up going to Google Search Gameland
anyway. So why get upset that we aren't helping that small handful when we couldn't care less about the other mass of the player base who isn't going to be helped by any variant rules? And on top of that... I think it is beneficial that these new DMs and players
learn about what actually is out there in Google Search Gameland by having to so! There's so much awesome stuff out there to find that I think expecting them to go in that direction is in fact the better way to approach things.
If anyone needs a variant rule... they will find infinitely more and better rules via a Google Search than they would from a chapter devoted to it in the DMG.
(And before anyone asks "How will these players know to do a Google Search to find new rules?" Come on. Let's be serious. Let's have a little faith in the most
obvious of choices we as humanity currently have to acquire new information.)