I wonder if there's a functional reason why they do this, rather than just implementing responsive design / media queries? I seem to remember more sites doing t

I wonder if there's a functional reason why they do this, rather than just implementing responsive design / media queries? I seem to remember more sites doing this ~5 years ago, but based on what I see, it has fallen out of favour. (Actually found some info if anyone is curious: https://medium.com/freely-sharing-the-sum-of-all-knowledge/why-does-wikipedia-in-2018-have-a-mobile-site-and-a-desktop-site-bc2982f30fb9 https://medium.com/freely-sharing-the-sum-of-all-knowledge/w.... Though the article helps explain some of the context and reasoning, I don't think it really justifies the divergent experience and imperceptible progress on improving the desktop experience)