We've collectively learned that besides the OPSEC concerns most of the "diary" type posting is very boring to consume (most people are boring) and therefore it's pretty likely your posts aren't that great either.

To make them interesting you must put effort, which we see some people doing, but anyone who has done it knows how the amount of effort needed detracts from the actual meaningful part of experiences/life/relationships.

In a way blogs are the worst medium now for this: Hard for people to consume casually, hard to meaningfully control the audience, and constantly scraped/archived by 3rd-parties. Most who still want to do this more causal, diary-type posting are better served by a private Instagram and posting occasionally, but mostly focusing on low-effort Stories. The key part/fix is the ephemeral nature of the majority of posts/content.

And there you see exactly how/why most people end up doing exactly that.