Re: Debian
The elephant is commercial software.
Commercial software needs to ship closed binaries, with some form of control over who downloads them and/or runs them (be that login, hardware dongle or online one-time validation).
That creates a lot of compatibility complications.
It also creates a testing issue. When there are contracts (and often lots of money) involved, customers have rather higher expectations that something is going to work.
You can get away with it never working when it's a massive bespoke government system, but not when it's tens of thousands of small customers.