You thought knowing and maintaing strong password is enough to guarantee access. Well Google disagrees with you.
Getting access to anything is suddenly hell. I explicitly disabled 2FA after encountering this bullshit once. Won’t risk losing my account again.
I’ve almost lost my Google account twice in less than a year due to Google’s terrible 2FA implementation.
I’ll take my chances thank you.
Personally I've also got it floating around one of my Linux devices with a small program I can run against it to display the codes, which came in handy when I switched phones and forgot to reload the GA app. (Yes, I know that this defeats some of the security of the second factor, with it supposedly being "something you have" that can't be easily reproduced).
If migrate to a different country and dont have access to your old number you will be in world of pain.
And "helps making this more efficient" ... well, a tiny bit more. Knowledge is power. Google posesses a lot of knowledge.
But even "only the ads". There are worlds between showing someone random ads, or a highly tailored custom one, made out of all the online and much offline activity of that person.
And knowing allmost all about what a company is doing and controlling their communication is potential valuable in various ways as well.