https://www.scmp.com/news/china/science/article/3255351/nasas-dream-comes-true-china-plans-build-giant-rail-gun-launch-hypersonic-planes-space
https://www.scmp.com/news/china/science/article/3255351/nasas-dream-comes-true-china-plans-build-giant-rail-gun-launch-hypersonic-planes-space
No rail launchers arent new, they just havent been invested in for space travel. At a guess id say because they are expensive and end up stuck in one place, which adds limitations later on