I think you're reading it wrong; the phrasing as I read it is consistent with your "frontend devs at the bottom of the pecking order" perception. The original quote says "good luck being treated like a real engineer" implying that frontend devs are treated so poorly they aren't even considered to be real engineers.

FWIW, frontend is a suite of hard problems which are distinct from the problems we face on the backend but no less challenging. Frontend development today certainly seems a lot less rigorous than backend development in the sense that there seem to be fewer best-practices and more of an embrace of a certain "cowboy/ninja/move-fast-and-break-things" chaotic ethic (engineers from other disciplines would balk at the characterization of backend engineering as 'rigorous', but I think it's fair to say that we devote more rigor to it than frontend development). I think this is largely due to our industry deciding that frontend was a low-skill position and thus putting most of our most junior engineers there to sort it out, and then we on the backend mock them for churning out new frameworks and tools in a desperate effort to bring some order to the chaos.

No, not a typo, just specific to Twitter. On Twitter, I seem to only find React-devs that gain any kind of fame, and then it's all a big circle of people who self-promote one another.

My personal guess is it's because front-end people can demo things easier.

I think amongst larger dev circles, it's probably generally true that front-end are considered towards the bottom. I think some front-end developers, like Dan Abramov, show that that's a bit unfounded.