[nurettin]

I've wondered what-if scenarios like this for a long time. I see them being implemented smaller websites, but never at scale like amazon.com or YouTube where they serve petabytes per second. My conclusion is: it gets so expensive to track and block users at session level that they just let go.

[Kadin]

That's only true if only a small percentage of users actually use that particular ad-blocking strategy. If a significant number of users did, then it would be a real concern.

Although I think YouTube et al see an increasing amount of revenue and viewership coming from apps... and if they could, I suspect they would kill their web sites in favor of apps where they have much more control.