I am absolutely not defending Comcast here but its worth pointing out that every anecdotal bit of evidence about performance and reliability can be true.
Network performance in that last mile can differ by block and even by season. An otherwise functional run of coax might have intermittent ingress but only shortly after it's rained while cold out.
This isn't even counting all of the flaky performance anecdotes that really boil down to overcrowded Wi-Fi or poorly configured consumer gear or anything else that isn't strictly the fault or problem of Comcast.
In college, we had the combination of spotty wifi + 10 dudes concurrently torrenting Shrek 2 + jank Android tablets running rogue DHCP servers and taking router's IP + rats chewing through cables, yet every time the internet went down, they called Comcast. And it was never actually Comcast's fault.