The only part of your post id like you to answer.
"All signs indicate that Halo Infinite is going full on GaaS mode though, that is where the idea that MS wants MTX in all of their games."
Where has MS said the full Halo Experience and all their games going forward are going to be GaaS games full with "needed" micro-transactions?.
A better way to put it for you. If say Horizon 2 launched and it was coming with 2 modes separate btw from each other You get the full single player experience. But then you can also download a free2play online mode that clearly is going to have cosmetic items for sale to keep up the costs for this free2play portion that people can play for nothing and in no way effects the single player portion that people who like single player games can buy. How does that effect you?.
Can you not see the difference here or is your bias clouding your judgment?.
You're assuming a free2play multiplayer mode that was built off the assets of the single player game would cost a significant amount of money to make. It doesn't. Your theoretical HZD2 multiplayer mode could be sold for $15 as a stand alone purchase, no MTX involved, and still make a ton of money.