Not really. Poco is much better proof of that, generally speaking. Regardless of what DxO says, OnePlus does not make great cameras. Great cameras require a lot of great engineers, which require a lot of money.
As for the other parts of the phone, well, they just aren't as demanding, OR people just don't care about it as much. People will pay a lot of money for a camera that is outstanding, vs say, a phone with the clearest voice imagineable.