Now, why am I seeing this factual comment in grey?

See here for instance a popsci take on the problem: https://www.scientificamerican.com/article/is-gravity-quantu...

Everybody expects a quantum theory of gravitation, but if we were drawing it from scratch no one would make it that weak. It is a difficult problem, people work in string theory because you can get Einstein's equations from strings and the alternatives look indeed worse. I don't think that means GR is a wrong take on gravitation, it's more like an amazing one to begin with.