In my area, I have access to Comcast and CenturyLink. My current Comcast speed is 200 Mbps. If I wanted CenturyLink, the fastest connection I could get is 5 Mbps for $50 a month. That's not enough bandwidth for my household. If CenturyLink offered service at 50 Mbps, I would switch in a second. But 5 Mbps is literally unusable in my household. Usually someone is streaming video while I play video games online.
Luckily my town just approved to build out municipal fiber, so I'll be getting that as soon as it's available. I am also moving soon, and I will look at what speeds I could get from CenturyLink at the new place. But for some people, just having an alternative isn't viable.