Don't CORS restrictions basically render this whole tool useless?
I use Postman a fair bit, and looking through my history it's mostly playing with 3rd party APIs to see what format they return and how they respond to query params and such. So it works for that purpose, since those generally won't have CORS restrictions.
It probably won't work for testing of your own API endpoints for, say, a SPA, though, which is likely to have CORS. But for local testing where I control the backend, I mostly just rely on printing responses to the terminal anyway.