This has not been my experience at all ... I run KDE + Fedora or Ubuntu on laptops for years as my daily driver doing professional work. Its an absolute joy to work with and stable. If there's a hickup then its because some unrelated process is consuming all memory or hogging all CPUs (Slack, Teams I'm looking at you) which would crash any desktop.

I get regular "crashes" on the newest Fedora KDE on a new Thinkpad X1 (from this year). I say "crashes" because it’s not the window manager or Wayland session crashing but some non-essential component of the Plasma desktop (don’t remember which one right now), so it doesn’t affect my work at all. From my point of view it basically just causes a crash report popup every 1-2 hours and says whatever service crashed has been restarted.

For me it happens when I forget Wireshark running for a bit too long...