I don't like renting my games. One of the nicest things about Steam is that I can still download and play the games I bought 17 years ago.

Also, if I need to choose my monopoly, I'll take Valve over Microsoft.

I kinda get it, but what is the practical difference between that and re-renting the game 17 years later? In both scenarios you depend on the game still being available. (the buy model make it easier to keep the game around on some disk for 17 years ofc.)

Why does the acquisition need to go through for Activision-Blizzard's titles to be on Xbox Game Pass?

Accounting and exclusivity. MS can try to make GamePass a gate for all future purchases, and the interchange cost is just moving money around inside MS at that point.

Because it goes from a hope to a rule. No need to hope that Diablo IV will be free on Gamepass, day 1 (and let's be serious, if ActiBlizz stays independent there is no hope in hell for this to happen) - but if the sale goes through then this will be reality.

Imagine Diablo IV or each of the Call of Duties... free... day 1. That is huge value. Something Steam can't compete with.