Even with places with competition, net neutrality is necessary. It's not just about tiered speeds, but access. Net neutrality mean if you pay for 50/50, you will get 50/50 no matter what site you're trying to access. Netflix is the most common example because they're in competition with ISPs that also provide cable, but it's not the only case. Let's say a news publication writes something negative about an ISP, they can't throttle access to that publication. It also helps level the playing field, in that large corporations can't bribe ISPs for priority. An up an coming small business, or Joe the blogger would not be able to compete with whatever arbitrary prices an ISP would set so that potential customers could access them.
Conservatives keep purposely misconstruing the argument to make it seem like NN is about everyone getting the same internet speeds, or fear-mongering that govt is taking over the internet, as if all the other things classified under title 2 have been taken over by the govt.