Shimano has always been one for replacing the whole unit. It’s a shame, their stuff works reliably well. My bike mechanic friends advise not specifying SRAM - while their customer service and documentation is readily available, it’s not durable. Shimano hydraulic brakes are the gold standard. SRAM might have been first out of the gate - but they had to initiate a recall for their road hydraulic system due to cold weather failure and I’ve heard it’s hard to get an Avid DOT fluid system to work just right.
with the explosion of e-bikes and electronic shifting(Di2, eTap, Campy EPS), the bike industry industry will have the same reckoning the automotive industry had before OBD-II.