Of course they only do it because it's inevitable, and they don't want others doing it before them.
But that does not make it "inevitable".
As such, I'm not sure where you'd like to draw the line. There's no obvious, defensible place to do it, not unless you're willing to go back up, expand the scope and fight the entire advertising industry on principle - in which case, I'll agree, because I believe that's where the problem originates and where it needs to be solved.
Market forces demand it, and people are beholden to the market so long as they exist within its sphere.
There are a plethora of other forces at work beyond "the market".
Yes, if no one imagines anything different the future will turn out as we expect. But with even small changes to legislation, norms and culture thing can turn out completely different. It is only inevitable if we resign ourselves to the status quo.
Those are the qualities that define "the market". What are the other forces you speak of?
Markets can change. They have many times before. But, and call me unimaginative if you will, I struggle to see why anyone would want to pay substantially more to ensure that comments on YouTube are written by a real, live human, let alone enough people to sustain the service. It is not like you are face-to-face at the bar. It is a blob of text that has always been disassociated from what human involvement there may have been behind the scenes.
Inevitable in the strictest literal sense may be too much, but the chances of the market changing here seem infinitesimally small to the point that "inevitable" is close enough.