I think you're missing you're also responsible for figuring out whether that Swagger documentation makes sense. It can be broken in various ways:
- missing (information about) authentication
- missing status codes that the endpoint in reality return
- query parameters marked as path parameters or vice versa
- spelling mistakes
- example request and response bodies that actually don't work or that are not consistent across endpoint
By coincidence I'm currently busy with testing APIs as well and at different times, I stumbled upon every one of the points above. Plus, a few times, the Swagger documentation was so wrong it couldn't even be generated properly, and so any paste and copy of the link into Postman proved useless.
To me, doing validation is not enough however I look at it. If you're tasked with this tiny subset of what you can do, it's still not enough to copy and paste the Swagger link into Postman and auto-generate a collection out of it. The difference between reality and Swagger could be bigger than what's acceptable. It's more likely that you'll need to figure out bits and pieces here and there and manually update the collection that was generated out of the Swagger.
Because the collection I'm working with was generated based on swagger spec that in its turn was generated from the code.
Auto-generation doesn't mean it was generated correctly. In suprisingly many instances, it's not because ... well I suppose the code could be a mess in the first place, so then the Swagger doesn't make sense either. So if you take it as a source of truth, you're trapped from the very beginning.