IABUK

Publishers get the short end of the stick with ad-supported content

Despite the fact that many publishers have struggled to transform
ad-supported content into profit, many publishers have opted to keep
the ad-supported content, and forgo a paywall.

And there’s a good reason why: it’s entirely unclear to many publishers
whether a paywall will be profitable or not, and once a paywall goes
up, a publisher’s audience will almost certainly drop. For many
publishers, ad-supported content and a large audience is still more
attractive than paid content and a smaller audience.