I am of the opinion that curl is better simply because you are already in the command line. You can use vim fzf or bash with it. Also curl will be the same on the day you die.
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.