Did this specific app actually "scam users out of their credentials?"
I'd expect that they didn't "scam" anything. The end user installed the app and voluntarily provided their credentials in order to access their content.
How is that a scam? If I'm using an Android phone and sideload an app to access say, HN, whether that's an apk from a publisher's website or from F-Droid, have I been scammed out of my HN credentials by that app's publisher?
If the app claimed to be the "official" app from Meta and used phishing techniques to get folks to install the app and/or reveal their credentials, that would be scamming.
But a deliberate choice by a user to use a specific app for a specific purpose, with the app in question actually serving that specific purpose doesn't seem like a "scam" to me.
Sure, Meta doesn't like it for a bunch of reasons. And it doesn't surprise me that they took action to smack these guys down. But characterizing this app as a "scam" doesn't seem to reflect reality.
Or am I missing something?
And in fact, sites are within their rights to determine which browser you can use to connect. Sites are often designed for and optimized around certain browsers and if they detect you running Internet Explorer 3, they can tell you to go away. This is a fact of the internet. And you're just as free to simply not go to their sites. This has been a fact for decades. No site is obligated to serve your obscure internet browser. And no API is obligated to serve every client that calls it.