

Yes, but it could have an option to choose desktop version on phone screen or download app.
They could even design a mobile friendly website.
If they are lying to you and you need to circumvent their demands, then that is asshole design in my view,.too.
Unsupported, with a screen not showing what it should means doesn’t work, for a non tech user. It’s deliberate misrepresentation. This is also called lying.
You can lie by omission. You can lie blatantly and you can lie by inference.
Sure, mobile responsive design can be frustrating. However, they are a giant company with billions in resources. They are not doing it to help users, they are doing it to force app downloads and data harvesting.