I'm not sure what you expect them to learn.
Only use "cleaner" ads ? It will pay less, ads don't pay much any more, you need the big, splashy, if-possible-exclusive-and-targeted ads to get money now.
Offer subscriptions ? They already do that, and they publish quality original content, so it's not the case of journal-X publishing the same press release as everyone and complaining that people don't subscribe.
At this point, they can only do two things with people who don't subscribe: block them from accessing content, thus losing lots of traffic and conversion possibilities, or show them intrusive ads, make a little money off of them, and hope a few subscribe.
One argument could be that "those ads are turning people off of subscribing and ultimately makes them lose money", but in every debate on this matter I have never seen it substantiated with actual numbers, and especially in the case of a household name like National Geographic I sincerely doubt it, at least not in any meaningful way.