It's called any kind of API or standard.
Standards make a platform easier to learn, understand, debate, debunk, and fix. They allow a larger community to share code and ideas, and provide a small degree of lock-in-proofing and future-proofing. Standards also allow transparent competition on the basis of implementation quality, tooling, SLA, etc., rather than obscuring those things behind incompatible facades (APIs).
New platforms on new technologies with no standards behind them can be a hard sell -- especially when they do not offer any new capabilities.
According to Techcrunch, Bungee is in a "freefall." And the interesting bit is that their CEO ascribed the recent round of layoffs to 'actual vs. anticipated rates of adoption.'
Now to be fair, there aren't a lot of alternatives in the absence of a standard. But ... it would make a lot more sense for all these players to get together and create some standard APIs and commit to using them. The APIs would cover all the basics: e.g., persistence (of object, key-value and relational flavors), templates, request/response handling, calls out to other web services and processing of their responses, publishing SOAP services (which still remains critical in the enterprise world), and interop with other server-side environments (Java, Python, etc.)
And these vendors would gain instant legitimacy by being founding contributors to a specific platform "trend," rather than lone voices in the woods. That legitimacy (and, via the sad logic of large companies, the "legitimacy" of being printed on the top of some conference bag) would help them appear credible to customers big enough to pay them real money.