The PS Vita predated the Switch by 6+ years... by the time emulation and CPU speed to match its requirements, it was already discontinued by Sony. It fulfilled its purpose.
The vita was a direct downgrade from a PSP if you valued fast loading times, emulation, homebrew and piracy. Even if you didn't pirate you gained the ability to rebuy your PSP games, and new expensive games with an OLED that had less battery life.
A downgrade from UMDs? Perhaps you're referring to the density of textures and newer, more demanding game engines, because the UMDs were such a pain. Trying hard not to get hyperbolic here.