I guess that depends.
If i wanted to buy a cartridge from whatever manufacturer, and they wouldnt let me buy one unless it was dealer fitted, i'd be extremely annoyed. I wouldnt buy it. I'd have to lug a 75kilo turntable to the dealers, spend an hour setting it up again, then explain to the dealer how my homemade tonearm works. Even if i had a standard TT i'd want to fit it myself, just so im 100% sure in my mind its fitted optimaly.
Obviously if i broke it i wouldnt be expecting to be able to return it LOL.
But, what can you do? Hard to treat it on a case by case basis, trying to judge the customers competance, so a blanket rule has to be made.
Obvious side to come down on is 'let the customer make his own choices/mistakes'. Its a free world, if someone wants to buy something they might break the first time they pick it up, thats up to them.
Obviously dealer fitment (free?) should be available if the customer wanted it.
So, dealer fitment should be free, highly recomended, but not mandatory!
Really sorry OP, i did sort of try and get you back OT but ive derailed it even more now:doh: