But it is a reasonable enough definition of it that we should be able to apply the principle of charity to calling it a failure, no? It is not something anyone would mistake for "success" on its own terms, even if the people involved did OK for themselves.
It really depends on the goal. It's a success if the goal was to build something to be IPO'd or acquired for benefit of investors and founders. It was a big success in that regard. It's a failure if the goal was mainly to benefit developers. That wasn't the main goal. Incentives like this are why I don't use VC-funded stuff unless I have a fall-back option. Risks also apply to proprietary software in general but many suppliers are more interested than startups are in sucking money out of you for long-term. Market leaders stick around longer.