At enterprise scale, locked down marketplaces don't work. They act as an forcing factor for larger organizations to build in house because no one wants vendor lock-in or to lose money via an arbitrage.
This is a major reason why you'll see large deals pushing for enhanced customization options or API parity, as larger customers have the ability to push back against vendor lock-in.
Furthermore, a relatively open market (eg. NGC) acts as a loss-leader by allowing a community to develop using a corporate standard, thus allowing you to build stickiness without directly impacting a customer's bottom-line
Fundamentally, a company driven by Enterprise revenue (eg. Nvidia) will have a different marketplace structure from a B2C product such as Apple's App Store where purchasers have little power.