Consider it, your are Deutsche Telekom, you release the Magenta System, do you want to put any effort to support any 3rd party device, but the ones what you sell. Of course not…
That’s why you would support the -D and not any other.
ZHA and Z2M is not interested about what is the identifier of the device when it is executing the assigned code, you can list as many identifier for the same code. Z2M has in the herdsman converter both the 3400 and 3400-D listed for the same code.
Or just as an other example centralite has 3200 smart sockets, a de and fr version, both has the same code in the herdsman converter.