They're the only main distro I know of that uses it at all by default.

Red Hat, Fedora, Debian, Ubuntu, Arch, etc. Ubuntu is the only one.

I have to say that I really do not understand the point of comments like this.

The reality of user-facing Linux is this:

Most of it is Android. It sells billions of units per year.

Of the rest, something like 90% is ChromeOS. That recruits 2-3 hundred million new hardware sales a year, which is roughly 10x as many users annually as the entire history of the Linux distro world. ChromeBooks sell more than desktop PCs and more than Macs by value although Macs cost at least 5x as much.

But of the remaining, oh let's be generous and say 10% of Linux users, most is Ubuntu.

Debian-based distros are 2/3 to 3/4 of all traceable measurable Linux usage, and 2/3 of Debian-family use is Ubuntu.

Red Hat and its fantastic valuation is like 1% of the Linux world.

So what you are saying is "only the Linux mainstream uses snap, and all the weird little hacker/hobbyist distros that have like ten users don't use it."