The only games that have CR are D&D and it's clones.
IMHO it is due to the scaling issues the game has because of constant HP inflation.
I have never been a fan of it - and other RPGs do not need it largely because they have much shallower power curves.
I have also yet to see many d20 based games go a low/Fixed HP route.
It seems that zero to hero is a hard habit to break.
It's not a bad habit, it's a feature. Perhaps the most important feature among the many that contributed to D&D's success. That's because it's a player rewards system, and a skill point here, a skill point there isn't as compelling as leveling up in D&D. UX studies show that people respond better to occasional big rewards than to more frequent incremental improvements. It sucks you in, and give you something to strive for. That's why it's so widely emulated in online games.
Though there's definitely an argument against infinite scaling. Perhaps the biggest problem is pragmatic: It's hard to balance across an infinite range. E6 recognized that in the d20 system, and capped the game at the sweet spot, allowing lateral improvements (more feats, more skill points), but not advancements (no to BAB increases, no new spell levels, etc.) after 6th level. Old school D&D has a cap at name level (9th in Basic, varies a bit in AD&D), but that's only really for hit points, and only partially (still get a flat bonus). Things like saves and to hit rolls cap later (up to about 21st level in AD&D1) or not at all, and spells not until archmagery (or high priests a few levels behind). I always thought converting old school D&D to a E6-equivalent (probably E9 or E10) would make an interesting variant. The trick is providing lateral improvements.