"Please spare me "just because Apple says they aren't doing it doesn't mean they aren't doing it"."
Why, have Apple done something to make you trust them implicitly? It's clear that once one company gets away with something the others will follow. Apple were the first to risk non-user replaceable batteries and were slated for it, now it's the norm across almost all devices.
You asked why Apple might do such a thing, the article gives you the answer. If their devices are lasting longer then they can't make the same amount of money from people upgrading constantly, so they will need to find another way to maintain their revenue stream.