There is this thing about quality, people do care ahout how well a piece is written, only it does not alwqs coincide with what the author would deem good writing. When the two match, you’ve got a winner. Enjoyable long-form is almost always wrapped into a story (as in real story-like story), with informational elements carefully woven into a proper narrative. This hasn’t changed since forever. Your readers' minds crave stories, and if you give them dry information instead, they will definitely “bounce”. E.g. this article is informative, but not at all engaging. It did require an effort to read it. People want reading (as everything in their lives) to be effortless. If a story flows, they flow with it.

Also there is the thing about what popular platforms and their editors push. The hype of “500 word blogpost” was originally meant to maximise ad impressions on specific media, but ended up helping to create the very trend you are lamenting above, but that is a much longer discussion.