It's because of that thread that people mistakenly believe you need a gmail.com address. A bunch of people in that thread guessed you needed a gmail.com address. Others immediately said no, you don't need it and showed examples.
But this is how misinformation spreads. Many people only read it and believe it without looking closer.
We just trust that other people know what they are talking about. :)
... Also I could be wrong, I'm trusting the counter examples in that thread. :D
You're not wrong, and it's easy to prove. Just go to the page where you create a new Google account, and select "Use my current email address instead". Then go to the page where you register to be a Chrome web store developer. You won't see any option forcing you to create a @gmail.com address.
But this is how misinformation spreads. Many people only read it and believe it without looking closer.
We just trust that other people know what they are talking about. :)
... Also I could be wrong, I'm trusting the counter examples in that thread. :D