If her label allowed her to be artistic throughout all those years they suppressed her to their basic standards, would she have been massively successful like Justin has with his artistic vision? Would her career be in a better state right now?

I don't get the question as Britney is far more successful than Justin was/is.

Britney had her success and fame that only few have reached that level and justin haven't reached half of it and we all know that she doesn't want that anymore
stop acting like her label and forcing her to do thing she doesn't want to
obviously she's sickin' tired of the music industry and since circus she basically said all i want is to live in an island with my children and my lover
let her retire and live her life as she wants to and stop criticizing her just because she lacks passion to do what is she told to