No, it's not a must. I used MX Linux many times in a Live Session using strictly the G.U.I. While I have nothing against anyone who likes to use the Command Line and I think it is good to learn it if you can. I am strongly against Command Line Junkies that push the Command Line like a drug pusher. In my experience trying to learn the Command Line is impossible in my case and I have given up on it since the Command Line has caused more trouble than I could shake a stick at. Twice it wiped out my distro that it required a complete re-install and many other headaches.
The more I learn about Linux...the more I'm using the Terminal and in some cases is easier.
The Terminal is part of Linux and everyone should have a basic knowledge of it...you never know you might like it.
If you run the wrong command and it screws your system...who's fault is that ? Terminal commands posted by me or anyone else on this Forum are safe...the Mods wouldn't allow harmful commands.
If a harmful command wiped my system...that's no problem because I have an image of my system on an external Drive created by Foxclone or Redorescue or both...it's a simple matter to put the image back with nothing lost.
Anyway we've all done the wipe the system thing...I did with GParted a few years ago but I had an image saved...lucky me.