By which metric? Distrowatch ranking?
Their page has this to say
"The DistroWatch Page Hit Ranking statistics are a light-hearted way of measuring the popularity of Linux distributions and other free operating systems among the visitors of this website. They correlate neither to usage nor to quality and should not be used to measure the market share of distributions. They simply show the number of times a distribution page on DistroWatch.com was accessed each day, nothing more." [0]
Wikimedia has completely different numbers. [1]
That being said, I think that we have reached a stage where its become very easy to switch between Linux Distros. I remember 5 years ago when I tried to switch from Ubuntu to something else, It was pretty noticeable (mostly because of font rendering). But these days I think the situation is much better, and I think it really speaks a lot about the progress that has been made on the usability aspect.
Is mint really the most popular distro? According to distrowatch, yes. But my suspicion is that mint users just like to tell everyone they are mint users. The majority of Ubuntu users probably just install it and go on with their lives.
I think a big factor is that if you google for "Linux Mint" the distrowatch page is one of the top results, while if you google for "Ubuntu Linux" you get other results instead.
That being said, I think that we have reached a stage where its become very easy to switch between Linux Distros. I remember 5 years ago when I tried to switch from Ubuntu to something else, It was pretty noticeable (mostly because of font rendering). But these days I think the situation is much better, and I think it really speaks a lot about the progress that has been made on the usability aspect.
[0]http://distrowatch.com/dwres.php?resource=popularity
[1]https://stats.wikimedia.org/wikimedia/squids/SquidReportOper...