My opinion is that "the big sellout" happened when apple introduced the iphone and the apple app store.
and it basically came down to a couple nuances in their policies...
#1 apps have unfettered network access
#2 apple would never approve security apps like a firewall (because #1)
and when a big player sets an example, it normalizes the situation for everyone else.
I think it was seen (or sold) as "advertising will fund everything" just like television, radio and print advertising did in the past.
Except the old advertising was one-way. Advertising today means ubiquitous surveillance and dossier building on every person on the planet.
It's been ~ 17 years of this iphone BS, and now behavior is creeping into every app, device and platform. Look at microsoft breaking new ground in appalling behavior with each software update.
Thank goodness for linux, open software, open hardware and people coming up with great hacks all the time.