Not a strong reason really. Snaps seem to cover a few apps that I use often than aren’t available on flatpak (e.g. Zerotier). Joplin is just an example but I’ve the same issue with all snaps. I like to run things from the command line often and that’s much better with snap. I’d kinda prefer to run all snap or all flatpak. It’s a bit easier to debug, if something goes wrong.