Not a downvoter, but systems "breaking" from a lack of characters isn't really a thing unless your dm refuses to do anything other than run prepublished material. Encounter difficulty, class based skill requirements, need for a healer, etc these are all things a campaign can take into account. Since they can be accounted for, the argument is null.
This is all the more true for solo rpgs. Certain systems at intro levels have deadly combat that could certainly easily kill a character, but again, that's assuming a lot. Combat doesn't necessarily end with death. It's certainly framed that way by many systems. But again, something that can be accounted for.
I think you're being downvoted because you've presented a binary statement that obviously overlooks the flexibility inherent in pen and paper games.
To respond to your request, I'll say Burning Wheel, Troika, Dnd (any.) Vampire the masquerade, or any other pen and paper game ever written. Is my gm going to kick me out of my solo game because I brought a homebrew character?
Your last point is curious. It supports my statements better than yours so I'm not sure what your point is? It leads me to believe I've somehow misunderstood what you are saying.
I'm sorry if this comes across as negative, that's not my intention. If you would like to post a rebuttal, I'm happy to consider it. It may help your previous statements by backing up those claims with thoughts that are more specific.
Regardless, I hope you have a lovely day.