With the spread of mobile devices, web sites have been checking whether the device is a mobile device and offering to display the mobile version of the site for years now.
Recently, a friend of mine sent a link to m.gag which I opened on my desktop. I was amazed that the site opened in the mobile version and would not even suggest using the desktop version (9gag). I looked further into it and this seems to be also a pattern with news paper sites, e.g. https:-//mobile.nytimes.com/ vs. https:-//www.nytimes.com/, (two Austrian news papers: https:-//mobil.derstandard.at/ vs. https:-//derstandard.at/ and https:-//m.kurier.at/ vs. https:-//kurier.at/)
Now to my main question: why is there this asymmetry of suggesting to display the mobile site or redirecting to it directly but not doing the same for mobile-to-desktop transitions?
(Sorry, since I'm new to this site I can't post more than two links in one post)
EDIT: This question does not ask whether two distinct sites for mobile and desktop are good or bad, and does not ask if there are advantages to having a distinct mobile site but my question comes down to:
Is there a reason why sites offer to display the mobile version when browsing the desktop version but do not offer to display the desktop version when surfing the mobile version?