I’m not seeing the connection you’re making between the admitted marvel of engineering at scale and ads.
Not sure what standard you are using for 'marvel of engineering' but to me this is truly a marvel of engineering.
[1] https://blog.youtube/inside-youtube/new-era-video-infrastruc...
Though I don’t think I have a specific standard, I’d have to think about it. “I’ll Know it When I See It” has historically been my personal standard.
Some other user mentioned that there “was no free lunch” but explicit ads before and during videos don’t have to be the payment for said lunch.