To use a metaphor: the internet is a mailperson, and a YouTube video is a package. The mailperson hands it off to me. Then I have to fumble with opening the box to get the item inside.
Well, let’s say I have a butler. The butler can take the package from the mailman, and rip out all the unnecessary stuff, and give me what’s inside the box. The butler is adblock.
YouTube/Google cannot mess with my butler. Why? Because it’s outside of their power. They can try to do things like force a signature before giving me the package. But guess what? My butler can sign off my package. YouTube knows to get to me, they have to go through my butler - period.
So there’s no “blocking traffic” because once the package is sent, they have to deal with my butler. And they can make all sorts of detectors on the package, but we’ll keep finding ways to bypass it and convince the package that my butler can totally sign for me.