Re throttling, as per the earlier answer, it is network congestion/backhaul contention. No conspiracy theory.
There is congestion to muddy the waters and some areas are worse than others even on fibre, but there's no way my ADSL2+ service has not been DLMed to half now as it's still rock solid at that any time of the night or day. Doesn't make much difference for general web surfing but it certainly would if you were a big downloader of data.
It was Netflix that tipped a bucket on the best laid plans of mice and men although to be fair the NBN is still a work in progress to get everyone on ASAP and then they'll have to address the congested areas seriously.