Gamers shouldn't cede so much control to some 3rd party who will be watching over their shoulder and collecting every scrap of data on them and their friends while they play. We don't need our performance in games being used to determine our physical and mental capabilities, our online chats being mined, or our social networks being graphed. When I fire up a single player PC game nobody is logging the days I play, or how many hours that I play to draw inferences about my life and responsibilities.
With very few exceptions, the games I play on my computer can't be remotely censored or modified against my will. Neither can the games on my shelf, and I can resell those too. Instead I retain the ability to mod games and alter their settings to my liking without anybody's approval even when the creators or publishers would disapprove.
All the benefits of Games-as-a-Service came with massive trade offs and provide far more benefit for the 3rd parties who would insert themselves between gamers and the games they want to play than they provide for gamers themselves.