I'm betting that Unity's customers, which includes a horde of mobile app developers, are a bit more demanding to have (and keep) than the few - if any? - outsid

I'm betting that Unity's customers, which includes a horde of mobile app developers, are a bit more demanding to have (and keep) than the few - if any? - outside Valve who license Source 2. It would be great if you could be Valve. Everyone wants to be Valve. But you are not Valve. Especially not if you're publicly traded or a private equity rollup - things Valve has stubbornly resisted becoming.