Regardless of the distro there are always folks who have problems with it. Most problems stem from user mistakes, inexperience and/or hardware incompatibility. (Disclaimer: I am a retired admin at KubuntuForums who has used KDE since SuSE made KDE 1.0 Alpha its DE in its 5.3 release in September of 1998. For the last three years I've been running KDE Neon User Edition on top of Btrfs as the root file system. I will never use a distro which doesn't offer Btrfs as a RFS.).
Mint is an excellent distro and most people, especially Linux novices, cannot go wrong choosing it. It's ease of use contributes, no doubt, to its continued high page ranking at DistroWatch. Many new users coming from Windows were drawn to KDE because it could be configured to look & feel like XP, NT, W2K, Win7 and Win8. No sane person wants to configure KDE5 to look and feel like Win10.
Now, users are drawn to KDE5 because of its beauty and power.
I tried Mint for a while, as I do many distros, to see what Mate and its other DE offerings were capable of. I also recently put Kubuntu 18.04 on my metal for a few days to see how it behaved. (Using Btrfs snapshots I can easily and quickly restore my Neon installation even after wiping the HD and giving it entirely to another distro. One Btrfs user, oshunluver, can boot from any one of six different distros using one grub menu on a single HD running Btrfs.) Having used Linux as my primary OS for 20 years you won't be surprised that I found both Mint and Kubuntu 18.04 to be stellar in their performance. Kubuntu 18.04's performance is due almost entirely to the KDE Plasma desktop. Running my NVidia GT 650M chip using the 390 driver on Kubuntu 18.04 gave Minecraft 600+ fps performance. Neon, on the Ubuntu 16.04 platform, running the NVidia 384 driver, gives between 400-500 fps. Btrfs is its usual faultless self on both Kubuntu and Neon. KDE Plasma 5.12.XX is a VERY powerful and VERY configurable DE. It can leave the novice bewildered and confused when attempting to add or reconfigure its settings. Experienced Linux users, however, will have few problems adapting to KDE5 Plasma's capabilities. And, if all the user does is browse the Internet, email and watch online videos it makes little difference which Linux distro they use.