I think it’s all about what max boost the manufacturer is comfortable for warranty. I think the Doo is 6-6.5 pounds of boost max. Sure they could let it rip to 12 pounds but the engine won’t live. Not sure how high the Polaris boost puts out, but it’s probably similar.
It's most likely linked to the compressor map of the turbocharger (size of the turbo)
Theoretically the engine sees no additional stress with the system just compensating for atmospheric pressure so even if the motor has to make 8.5 lbs at 10K the hp output is still 180. Although if it is truly making 15 more hp than this years it will be 190+ according to the dyno numbers I've seen.
With that said, a larger turbo does introduce more lag...all things equal.
My guess is why not? Going from 160-180 gets everyone selling last years sled and buying a new one. They have to leave something on the table to tempt you into buying a 2024