High last mile oversubscription is a net good for home consumers, it almost always works out in everyone's favor. The exception is that 1 guy in 10000 that will actually somehow use 20 gbps a day all day every day in some neighborhood and create some drama in the news because ISPs can't be bothered to try to explain why oversubscription is good to everyone who already doubts them.
Or before you can no longer claim that you are delivering 1 Gbps.
Your average residential user does not move that much traffic at all, if you have a traffic chart that's something like 60s SNMP interface bit counter poller interval for their CPE, fed into a time series db, and draw grafana charts for that customer over a 1 day or 1 week or 1 month period of time.
Even when a customer does something like buy several new 140GB xbox games in one day, the actual amount of time that they're really utilizing that link near full capacity in the same 24 hour period is very minimal.
The only caveat is that you need to be able to watch out for the 1 or 2% of outlier/heavy use customers who will really use their link for huge amounts of data. In many neighborhoods there won't be any of those.
I'm not saying this as anti-PON, just that the existing coax improvements are sometimes very sensible and extremely comparable in the current generation. I've architected and deployed several small city G-PON and 10G-PON networks with Nokia gear and it's fantastic for net new and probably the only real option to continue growing 5-10 years from now. That said, if you've already got decent coax for the last mile DOCSIS 3.1 can be extremely comparable and behave near identically at the moment.
If you look at a typical residential 16:1 or 32:1 split XGSPON system on an optical spectrum analyzer that's capable of all DWDM ranges, it looks gapingly empty. There's just a few channels used for the downstream and upstream with the timeslicing for the various CPEs' usage. And vast ranges of totally empty optical space.
What I find interesting is that your average residential user does NOT really use much more traffic in (in average Mbps per CPE or GB per month) if you give them a 2.5Gbps or 5 Gbps or 10 Gbps connection. I have plenty of 2.5Gbps and 5 Gbps and 10 Gbps customers. Maybe 1-2% of them are really heavy users. The rest of them use exactly the same amount of traffic as the 1 Gbps users, because the vast majority of non-technical residential end users these days have only wifi client devices. Finding someone who has a desktop PC with a 1000BaseT or 2.5GBaseT LAN port to do a proper speed test is maybe 1 in 50 customers.
Even if you've got people with 3x3 802.11ax stuff running in 80 MHz channels they're just barely going to approach 900 Mbp speed tests downstream one way.
If we had offered 10G FTTH to the home in 2002 the sort of power user who would buy that might actually try to run a small server farm out of their spare bedroom. But now it's 2024 and people who are serious about hosting their own stuff are doing it with their own VM/VPS/cloud based stuff, or by colocating a few servers, etc. They know that a residential last mile gigabit+ connection is not the best place for it. There's outliers and exceptions of course, but they're getting even rarer every year as a percentage of the total customers (eg: someone who wants to run a torrent seedbox from their house or something).