Earlier quoted context omitted.
Actually, I am asking that. Several other commentors have asserted that "the world changed" a few years before the rule passed, yet nobody has really explained in detail how. So far I've gotten a hypothetical about Wal-Mart paying ISPs to destroy Amazon, which didn't actually happen. (Though I haven't read other responses yet, so maybe there's something more here I just have missed.) But, let's take a closer look at…
The reason FCC made change in 2015, because in 2014 court ruled that with prior classification, FCC had no authority to enforce anything unless they reclassify the Internet. Before the ruling, the companies were still respecting what FCC said (here are some cases that happened between 2002 (when FCC reclassified Internet as a telecommunication service) and 2015[1]), now the cat is out of the bag. Also note that 2015…
I'm cherrypicking here, but as an avid Bittorrent user, I remember there being significant debate with the community about the extent and methods that Comcast was using to "throttle" Bittorrent. (And I can honestly say that I was never impacted by them.) And I say this as someone who despises Comcast (regretfully, I'm stuck with them even today).
In any case, it doesn't pop out at me that many of those violations were actually mitigated by the FCC. E.g. Google Wallet got blocked, but Isis(sic)/Softcard was just terrible. By the time it was dying, carriers were letting Google Wallet through and then Apple Pay paved the way for Android Pay.
And actually a few of them (like zero-rating in the case of MetroPCS), aren't negative in my mind. I get the "startups can't compete" thing, but particularly mobile data cabs are still necessary today, and I'm okay with innovative, pro-consumer pricing models that get mobile internet into the hands of more people (which is intuitively going to happen when non-incumbents are the ones doing the innovating).