FWIW I've found mixxx to be much more stable than serato or traktor (commercial stuff). I can't say whether they focus on bugs or features like your criticism suggests.
As a Mixxx user of 8 years with many life shows and even longer ones at home I have never had Mixxx crash on me, not even once.
I had some UI annoyances, so I support the effort and trust the devs to make the right choice. Otherwise I can still just run the old version till 3.x turns stable.
I have no problems with Mixxx in that regard. I run it on Linux and for me it is rock solid. It can't help if your computer crashes though.
I used to use mpd for a while which automatically continues playing where it left off after a reboot.
What I learned from that phase is that the music I enjoy in the evening is rarely the same I like blasted in my ears mid-song at full volume in the morning. Terribly annoying feature, will not use again.
Not crashing during playback.
But hey why refine and fix bugs when you can constantly iterate on new features no one asked for (sadly this applies to most open source software).