Totally, and even though I only used first party or about-to-be-first party games, increased spending on microtransactions would make third-party studios happy too. The 70% MS wouldn’t be getting would probably be worth enticing devs and publishers, and the content keeps flowing. Besides, MS would be getting 30% of a much bigger pie.
And yeah, it’s going to be very hard for Sony to make a case when the proposition becomes:
“I could spend $70 to buy the new Call of Duty on a PlayStation 5 I can’t find, or I could split that across my 4 friends who play it with me and we could get 14 months of Game Pass Ultimate, which also gives a 10% discount on all microtransactions and since we’re casuals we can get the Series S which is cheap and relatively easy to find.”
If there’s a way to do like a digital escrow where people deposit the money, I could see pairing up with internet friends or even people on message boards or Twitter or whatever normal people use. Either you agree to join in for a year or something and deposit that amount into the escrow account or you do a thing where you have until such and such date to throw in your portion or you get removed? Not sure how feasible that is.
Edit: A post by a MS employee on another forum sheds some light on limitations:
[T]here is a yearly limit to the number of different people that can invited (to prevent a monthly rotation of accounts being added) and a yearly limit to the number of different family plans you can join (to prevent users bouncing around between spare slots in family plans).