Ugh... I'm sure you mean something different than I do when you say "Proprietary." The only thing proprietary about D-STAR is that Icom owns the trademark on the name... The specifications are otherwise open to the public to read and Patent free. Not only that, but Kenwood has produced D-STAR radios, and using an MMDVM and some open source software, you too can build a D-STAR radio.

DMR is also a published standard, it is also supported by multiple manufacturers, it is also protected by a mountain of parents that manufacturers have to pay Motorola for. Using an MMDVM and open source software, you can build a DMR radio, but if you sell it, you will owe Motorola a mountain of cash. I'm certain your definition will disagree with mine... I would argue that's more "Proprietary," despite there being more manufacturers producing it.

Both use vocoders that are both secret and protected by patents, there are both stollen and reverse engineered implementations, but they are probably all illegal... One might call that "Proprietary," but if one does, all digital voice modes that one can purchase are proprietary, including D-STAR, DMR, System Fusion, P25, and NXDN.

If you hold such a definition, the only digital voice mode that isn't "Proprietary" is M17, and zero manufacturers produce radios for that... So if manufacturer count defines "Proprietary," does M17 even exist? (It does...)

D-STAR was popular because it was cheaper. Now DMR is popular because it's cheaper. Why would anything other than price drive popularity?