Then it seems that blocking ads is the more honest thing to do! Otherwise the company placing the ad would be unfairly paying money for a service not actually delivered. This also makes the market more efficient, as blocking ads is a clear signal their products aren't desired.
Except TV and YouTube can offer similar, but not necessarily same, purpose.
TV, speaking of cable, is exclusively for entertainment. YouTube is used for pretty much everything these days. Imagine being in a panic, looking for a video how perform CPR, and getting 30 seconds unskippable ad.
Principally - the latter actually affects the compensation given to the creator of whatever video you're watching. The former does not.