I mean, it probably wants to make sure you’re using the API for programmatic access so they can charge you for it instead of having you abuse the free tier.
Not sure if they’re still around, but in the early days, before the API was released, there were some libraries that simply accessed the browser interface to let you programmatically create chat completions. I believe the first ChatGPT Twitter bot was implemented like that.
This post isn’t so much about whether it’s necessary from a technical standpoint (it likely is), it’s just an observation on the sheer irony and annoyance of it being that way, that’s all.