As a creative, criticism is important.
As a creative, armchair "I would simply..." style critique is not helpful.
I totally agree! This type of feedback or critique is not useful to the creator, and is in fact more likely to be detrimental.
But really there are multiple types of criticism, right? The first type of criticism is direct feedback, what I would would usually think of as critique, where you are trying to help someone else improve their work. This might take the form of analyzing what they've done and giving feedback on what you think they should specifically change, it might take the form of analyzing where you think they're going awry and letting them know without suggesting exact changes, it might take the form of simply experiencing the thing and telling them your reactions. And these require decreasing levels of expertise--the specific changes would probably come from a project director or maybe a script doctor type of person, looking at where things are going awry might be a colleague, experiencing the thing is something a layman could do.
The second type of criticism is discussion. You're not trying to help anybody improve, you're reacting to a thing--casually chatting about it, or having a thoughtful discussion, or giving your personal review. You're expressing your feelings about a thing, engaging with other people about it. You might do any of the three critique-style things, talk about what should specifically be changed, or analyzing what's wrong, or just giving your reaction. The key is that this is not intended as feedback to help the creator! The lines can blur somewhat these days when we put our takes on social media where a creator could potentially see them and be bothered, or in some cases we might even think we're doing something like offering critique and try to actually @ the person who made a thing. Unsolicited feedback is honestly kind of rude. But it's fine to simply have opinions about things and then talk about them.
Unless there's some missing context, the person being responded to here was just engaging in discussion. "Here's how I would remake Season 8 of Game of Thrones" was a thought exercise a lot of people did (and usually with orders of magnitude more vitriol), and I think people generally understood it was discussion, not an effort to tell the showrunners how they should've done things. Or even an effort to improve their own personal storytelling skills. That's essentially what this person is doing--people seem to broadly agree that the character designs in Concord don't work, this person wanted to try to rework one to see if they could figure out where things went wrong, adding to the conversation and potentially improving their own skills in the process. Arguably it's a little insensitive to do on social media while the people involved are probably worrying about whether they'll still have a job next week, but that's kind of unavoidable with social media.
Anyway didn't mean to turn this into a lecture, this was intended as discussion. :P