many obvious reasons (I'm in the US and the last thing I want to provide to the world is my phone number for MORE stupid spam. My address is absolutely out of the question, not in these times. It sounds alarmist until you get physical death threats from people that may or may not have to even do with your app).
But for reference, this author is in the Neverlands and things that seem trivial for US businesses are apparently more involved over there. These small 30 euro costs aren't worth it to update some 10 year old app you'd only update if you just needed some trivial migration updates.