not at all. mint offers a bunch of features ‘exclusive’ to mint as an integration with their system. of course it’s all open source and you could install it on any other system. but the key important factor with mint is that everything ‘just works’ with a fresh install, no customization necessary - which is something that can’t be said about any other distro, including Ubuntu. it is the only distro i recommend for non-pc users as there is no chance they will brick it.
regardless, KDE is just a DE. you won’t get the same mint experience of course, since it isn’t officially supported (and indeed, only cinnamon offers the complete mint experience), but installing KDE on mint is easy enough if you insist on using it.