Basically, if all I can read is a headline how can I consider it informative? A news headline has as much evidence as your average Tweet, and can be deeply incorrect through the use of clickbait.
I do use methods to get around paywalls, but knowing that some/most people won’t, it seems counter-informative to solely use the clickbait headline to keep people informed.
To be fair, I don’t actually know if the article has a paywall or not anymore since I started using Bypass Paywalls on Firefox.