> it's reasonable to assume that all the other repair shops are seeing similar numbers.

I don't know, it depends on how many the author actually spoke to and how he came by them. If he found them because he saw them all talking about this problem, that's not a statistically reliable means of sampling repair shops. His selection was biased and driven by the issue.

> It's definitely not reasonable to assume that the only iPhones that are failing are the ones served by that handful of repair shops.

I didn't. Read my comment again.