Where are you reading the bolded? 99% of this thread is about content ID matches, which prevent you from monetizing but don't remove the video and don't endanger your account.
It's more of speculation drawn from recent events I suppose, so I should have separated that from the rest of my points. If I recall correctly nintendo has been cracking down on people posting videos of their games on youtube, giving them copyright claims. So that would be a copyright strike on your account, which many youtube partners won't accept an applicant to have. Get enough strikes and your account is deleted. So for small time youtubers who have yet to monetize their videos (like me), it can be hazardous. All it takes is one person in the company to decide they don't like the video and you get a copyright claim.
But what happens when a famous youtuber gets tagged, and isn't eligible for monetization? As far as I can see this will apply to all the youtube personalities that post gameplay videos with ads. So it will send a message that youtube videos cannot make money, and if they do, they shouldn't be. Then what happens when they host the youtube video on their site and ask for donations; or ask for donations in the video itself?
Could they try and go after that money? They are getting money from donations, people are donating for the content, and the content provided is the games. So will the industry try something to make that difficult for those doing it? Providing game videos are a gray area, but as long as they fall under fair use they should be fine, monetized or not.