There's a way to critique something that actually explores the nuance of it, and then there's just saying that something is "bad" or has "declined in quality". It doesn't give anything. You don't have to be a musician to have an opinion on music, but you'd better at least be able to articulate a meaningful position if you expect people to read paragraphs upon paragraphs of your opinions.

This isn't a thoughtful analysis that demonstrates an understanding of the nuances or story structure or that intelligently explores the strengths and weaknesses of each season. It's someone who has nothing meaningful to say spouting their opinion with as much fluff as possible, and passing judgement on something they wouldn't be capable of meaningfully contributing to if given a century.

The only really substantial criticism presented here is the idea that the show is more into its own lore than the author is interested in. That's less a statement about the show than the author's tastes, but it's at least substantive. It's something other than just pointing and saying bad. "Costlier but inferior" followed by a brief plot recap is not a meaningful artistic critique. Arguably, though, even their actual meaningful criticism that it's too into its own story is a pretty weak one. Every show isn't meant to be easily accessible to people who aren't caught up, and every show doesn't need plot-light episodes.

There's a lot to be said about Stranger Things as an example of an influential show that's very much wrapped up in its own story, but this spends a whole lot of time managing not to find any of it.