Pretty sure all the early CVTs held a constant RPM at max throttle since its most efficient, and consumer backlash was huge. People hated the feeling/noise, and so I think the marketing department won and said "hey, engineers, our job is to sell cars and people don't like how it feels so make it feel... normal", and I'm sure many engineers facepalmed but the consumer is always right.I think its not designed to run for 15 seconds at that rpm.
I mean even a small child if you ask them "make race car sounds!" they'll go vroom, vroooom, vrooooooom through the gears, they don't just screech "WWEEEEE" making a redline noise for 16 seconds.
Even though I know better, the constant RPM acceleration almost sounds broken in the sound example of different transmissions: