Well everyone is entitled to their opinion but again I can only speak from my own experience. In just one example from last summer I had a diver free flow at about 100 feet in the Great Lakes in 40 degree water. I helped them back to the line and up luckily making it to the surface right as the last of their air ran out. When I checked the divers IP on the reg at the surface it was well outside of spec. I asked when the reg was serviced it had been two and half years. As lubricants are wore away and certain parts wear it changes how the reg functions.I suspect that is a bunch of crap. How about linking us to those reports of diver casualties due to failure to maintain gear IAW manufacturer recommendations.
I personally find the Manufacturer recommended service interval to be extremely safe-sided (profit-sided) for divers who take good care of their equipment. BUT, if you do intend to follow the mfgr service recommendations, it does make sense to pay a bit more (even quite a bit more) to obtain free parts.
Again everyone is entitled to their opinion but our sport takes place in an unforgiving environment and the more challenging the dive the tighter the window gets. I encourage people use common sense and make sure that they safe guard themselves by keeping their gear in good working order. Oh and if you haven't been trained to service your own specific model of gear don't. 80 feet down isn't where you want to realize you made a mistake.