What you quote could be summarised as "frequent small posts work better than long infrequent ones". I kinda agree that's an incentive for lower quality (since quality takes time), but it's still a bit tangential.
What LinkedIn rewards are posts that get a lot of reactions and comments, which in theory sounds like a good metric. But when a metric becomes a target, it ceases to be a good metric, and that's quite visible with all the cringe "comment $keyword to get my free guide" posts.
Personally, I take the conscious hit on my business and don't play that game. But I'm pretty convinced that I would be more successful if I played it, and I'm still looking for a way to do it that doesn't feel wrong to me.
At the end of the day, marketing is not about reaching people just like myself. It's about reaching potential buyers. And the key question to me becomes what the "LinkedIn" in "LinkedIn rewards mediocrity" really is. Is it the platform with its algorithms? Or is it rather the audience itself?
We all gotta find buyers. Sometimes in the form of employers, sometimes in the form of clients, sometimes consumers. But whatever we have to offer, we need to find people interested in it. And while I have a good network that got me buyers throughout my career, not everybody gets lucky like that, so I try not to look down on them for using LinkedIn to that end.