I have had no problem getting warranty service from my local dealer, even though they did not sell me my RV. I have purchased one from them in the past, but that is not something I have mentioned to the service writer. They do have a very long lead time and that has caused me to go elsewhere at times, but that was my choice.
When I was still under warranty and had troubles on the road, Newmar was able to find a dealer on my route to assist.
I think the dealerships that act this way are ones that will not be Newmar dealers for long.
2013 Newmar Dutchstar 4347, Active Air
2019 DSDP 4369 * FREIGHTLINER XCR * HWH ACTIVE AIR
NHSO (Newmar Hoot, Sevierville Original), Kindness Matters