It seems to me at its root, that it's a question of available ad attention, and the value thereof.

The classic value prop for ads has been so badly destroyed by bad curation and content invasiveness that the basis value of that attention has dropped trough the floor. The growing prevalence of ad blocking is only a symptom of that.

This has become bad enough it even invades special interest nonprofit rags like the AAA, American Legion, and USPSA newsletters, for example.