Perhaps being one of the first major Distros in the sense of being easy enough for many less tech inclined to switch from windows and not need to know as much command line.
I had tried older and other versions of Linux but back then Ubuntu mostly just worked. Being a leader in that sense has held them in the place where its safe to dive into Linux despite the various other flavors that can do it better. The PR is a lot to overcome for newbies that are overwhelmed on it. It’s only later after getting a footing you will be brave enough to try over flavours.
For me Linux Mint is a no brainer place to start with my older hardware than Ubuntu now but I don’t think they have the word of mouth like Ubuntu. At least with Ubuntu if they are even aware of something more than Mac or Windows they have probably heard of the name not really knowing what it is. Many aren’t Googling Arch for first time installs I suspect.