Why? It auto-connects to the internet, which should be the absolute minimum of any LiveCD. It's layout is intuitive, which makes it easy to find whatever you're looking for. Has its own instructional manual for new users:

https://mxlinux.org/manuals/

Its forum is not overpopulated with snotty nerds that hate newbies:

https://forum.mxlinux.org/

It gets good reviews pretty much across the board:

https://www.dedoimedo.com/computers/best-distro-2019.html

https://www.techbrackets.com/mx-linux-review/

https://www.youtube.com/watch?v=gevOkYM7SA8&fbclid=IwAR31SIpENLsy9eW2OtsqjnJPG0G6JJNNELu4niA2751xTWURi45D_zIS4mA

It should be more popular than it is....especially with newbies and Windows expats.