Because it’s impossible to block adblocking. The server can’t know whether the client plays the video. The best they could do is have you wait the ad-time even if the ad is blocked but that would just mess with their analytics - they want to be sure the ad is being watched.
The only reason adblock blocking works for smaller websites is because adblockers need to catch up with each implementation. People will easily catch up with Youtube as there are thousands of people working on Youtube programming.
I think multiple accounts is a great idea.
I work in tech security and I cringe in pain when I see people post their 10 year accounts. The amount you can deduce and learn from mined social media data is absurd. I migrate to a new account every 6 months and that’s the longest you should keep an account. This of course doesn’t apply to your public brand account.