The point is certainly to integrate those communities, but if no one uses the high speed rail already there then building more is just excess production that will not be used and be abandoned eventually. Same thing with the highways, the last round of one's built out aren't being used yet there are still proposals approved for more, at the same time as approvals for high speed rail in areas where there's no ridership to support it, both certainly don't need to be there. If we were in full communism whatever, but we're not and rail lines that don't get ridership will be abandoned and rot. Even in full communism, we shouldn't build stuff that's excessive use of resources. One recent example of the overbuilding is the Lhasa ring road. Lhasa is not growing much at all and has like 280 thousand people, it doesn't need a 12 lane 100km ring road. Yet a massive ring road got made that doesn't see much use.

The old track article yeah is more about some of the much older track, I just cited it for how much abandoned rail there is which as far as I know there's no statistics on the split between how old different amounts are. Better stat would be underused high speed track.