not true, a couple of content creators have moved to rs3 but they don't represent the entire population
source:
https://www.misplaceditems.com/rs_to...l=week&total=1
In terms of stagnation, OSRS servers is what RSPS players have become used to, and what they want.
RSPS is a business, why take the risk with something entirely unique (OSRS servers are still different to one another), when you can just launch another oldschool server and rake in the cash (easier said than done obviously).
Unique servers *have* been done, even recently, but players don't want it.
That being said, 'different servers' are being worked on as we speak, i.e. Nalore, so it will be interesting to see how that goes, but for now OSRS servers are the 'safe bet'.