Depends to a point on the dealership in question.
I have had very mixed experiences from different dealers of various brands. Local VX dealer was very good as when the ownership changed a while after bankruptcy, most of the staff returned to the new dealership. Apart from the Omegas, all my Vauxhalls were supplied by them, both new and used.
I have also had pretty mixed experience between various people in the same dealership and even department. Although if I find a good person in a reasonably convenient location, then I will tend to stick with them.
Obviously some places are more receptive than others if you make it clear that you will do your own work.
I am not afraid to put a car in to keep the book stamped, for example to maintain the Mobilio warranty, but even then I will do the things I can outside of the service/warranty restrictions. Equally, if a car is out of warranty, then there's no concerns with doing it all myself, and when it comes to selling, having a stack of receipts and obviously replaced parts helps to sell a car as it demonstrates that the add isn't full of shit.
The chap who bought The Barge got more receipts from my ownership than the previous owner had handed over after a decade, and not being mechanically minded had arranged to consult with his local Merc specialist about the car and I was able to answer all of their combined questions satisfactorily.