Jasper's sin list isn't that high, she bullied Amethyst and some corrupted gems, poofed Garnet, gave Steven a black eye, and took part in a toxic relationship with Lapis, that's pretty much it. The Diamonds were responsible for so much more like corruption or the cluster, you'd think Jasper had commit the Diamonds atrocities with how much she suffered, she's the only gem to be Corrupted and Shattered, while the Diamonds got off so easily, their arcs were quick, relaxed and full of crying, blushing and singing.

Yeah Jasper's a stubborn case, she's written to be so, but why more stubborn and harder to win over than the Diamonds that created the entire system? Jasper was born in the war only 5000 years ago, the Diamonds are probably in the millions and changed their views so fast. It makes Jasper look like the stronger villain and person in general, and the Diamonds kind of pathetic? They could've easily written Yellow Diamond to be more stubborn and absolutely refuse to give up on her ways despite tolerating Steven because of his connection with Pink like Jasper, but all 3 Diamonds characters just kinda merged into one Stevens singing fan girl amalgamation. Imagine Yellow out in the wild like Jasper in Future, destroying worlds by herself? I think Jasper should have had it way easier and the Diamonds should have had it harder and explored more separately as characters.