This is pretty breathless reporting for iFixit. We can all draw whatever conclusions we want based on anecdotes. For example, I know a lot of people who have iPhone 6 and 6S phones and none of them have had this problem. But let's look at some numbers; the article mentions that all of these repairers see "several a week." Let's round up and say that's 4 a week, or 208 per year per repair shop. They only mention a few…
Even under your hypotheses, I'd say 100,000 faulty devices is already a very significant amount. In terms of retail price, we're looking at more than 60 million USD, and 100,000 customers who were sold a (possibly) flawed device. I'm not sure what perspective should be taken into account, but I'm pretty sure we should not be simply looking at whether the rate of failures is above or below 1% given the volumes involve…
If you want to take the view that if Apple sells you a faulty device they should repair it for free regardless of whether you're the only person in the world who has the issue; I would agree as long as the device is still under warranty. My guess is these aren't or the people wouldn't be taking them to third party repair shops.