Not only this, but it's worse for the fact that it's in a web browser, vs just being a native app that could be sold once, or at least with a yearly subscription for maintenance at 1/10th of the cost.
The problem is that they realised they could make more money by trying to lock companies into a proprietary API definition platform – they want the design, testing, QA, documentation, etc, all to happen in Postman.
I guess my point here is that being closed is directly against the goals of the technology. Apple's lock-in is either a side effect or potentially even beneficial to their goal of providing a good phone/computer/whatever, whereas commercial lock-in is fairly clearly opposed to creating an API ecosystem that is usable across a range of technologies/consumers/etc.
The problem is that they realised they could make more money by trying to lock companies into a proprietary API definition platform – they want the design, testing, QA, documentation, etc, all to happen in Postman.