No more having debates with people in call centres often in far away places speaking broken english about whether your broadband has a speed fault. Fibre either works or not. Clear cut and dry. Less hassle all round, along with the reliability, and oh yes that fast speed helps make the case too!
That just isn't the reality.
Only a small number of support calls to ISP's will be due to slow sync speed which is down to the copper xDSL link.
ISP's will still have congestion.
Customers will still phone up complaining the internet is too slow.
Customers will still have to deal with foreign call centres asking you to run tests and reboot your device. It will just be an ONT instead of a modem.