I've actually worked in this area. You are basically correct.
Sometimes you have to make a choice on which brands/chipsets you support. Devices on different ends of the compatibility spectrum can basically be mutually exclusive. IIRC if you advertise A2DP some devices supporting only HSP won't work, so you can make some hacky workaround but then your nicer A2DP equipment is harder to use. If you only need to guarantee support for X subset of devices you control, it's easy to tweak the settings so they work well together.
Sometimes you have to make a choice on which brands/chipsets you support. Devices on different ends of the compatibility spectrum can basically be mutually exclusive. IIRC if you advertise A2DP some devices supporting only HSP won't work, so you can make some hacky workaround but then your nicer A2DP equipment is harder to use. If you only need to guarantee support for X subset of devices you control, it's easy to tweak the settings so they work well together.