Features in old renderer pipeline not in URP

The thing I always question is everything was there in the old renderer pipeline; SSR, deferred rendering, all anti aliasing options, etc. so why weren’t those added into URP from the beginning since there were able to get them working in the old renderer pipeline?

To keep the performance safety… Don’t lets the user to use performance killer features

You are limited on the performance safety range of features when you are using URP