The bottleneck was the phone line running into individual houses. ie The "last mile" was a bottleneck. Dial-up. If you're old enough you will remember people connected to the internet via Dial-up, that is, their phone line. It was a bottleneck. It's data capacity was nowhere near what the fiber was.
But that buildout brought FTTN (cell towers, DSLAMs and DOCSIS) because loads was overinstalled in places that made little economic sense at the time.