requires a fair bit of post-installation configuration (suboptimal OOTB experience for newbies)
I’m not the biggest fan of Gnome’s defaults but the regular, non-techie users want a browser (maybe Chrome instead of Firefox, depending on preference) and possibly Steam for gaming. Both are on Flathub, available from Gnome Software.
Less software availability compared to Ubuntu or Mint
The software that isn’t available, isn’t of interest to newbie/non-techie users.
More likely to break than Ubuntu or Mint
If anything causes breakage, it’s those web tutorials telling inexperienced users to add a bunch of PPAs to do shit. “So you use Ubuntu but video playback is a big laggy on your super new, hardly upstream-supported Radeon graphics card? Easy, add this PPA with untested git snapshots of Mesa and Kernel.” Yeah, no.