Because so far, not a single YouTube update has let them get past it. Basically, I switched adblockers but forgot to uninstall the old one, then by the time I noticed, I had also noticed that the combination somehow, for some bizarre reason, ends up confusing anti adblockers to the point of not even getting "disable adblocker" messages. It's not something involving their blacklists either because they have the same blacklist (due to the aforementioned replacing one with another then forgetting to uninstall the older one)
I have only uBlock Origin and no YouTube update has gotten past it (except the first one for a few hours), I never get "disable adblocker" messages either. Also anti adblockers are not blacklist based.