I believe that this logic / workflow would also make sense for pretty much all private content in most Discourse instances - and would be superior to the status quo (i.e the built-in “Login Required” setting).
Many of our users hit that same wall when they respond to a notification or a link, but the site isn’t logged in on their device. And they frequently also bounce off it as you describe, saying “it is too hard, I didn’t know if I was in the right place, etc etc”.
I can imagine some sites where privacy is paramount, and where a teaser might not be appropriate. But these are likely in the minority - and the current ‘wall’ really isn’t a great experience for people and at the least could be improved.
Are you able to share more about how you’ve achieved this? Is it via a custom plugin?