normal domestic users would see little benefit.
Indeed.
Having on multiple occasions had the opportunity to plug my laptop straight into a 1Gb switch fed off a 10Gb symmetric internet connection , I can tell you that whilst the download speed is great fun (and very useful for things like software updates, streaming etc.), at a personal level I found very little use for the large upload capacity.
The downside is you soon discover capacity issues elsewhere on the internet ...
(e.g. the website you're visiting is slow because of load or they've got slow connectivity)
At a business level, of course there are a whole multitude of uses for a symmetric connection .... email servers, VPN connectivity to other sites.... but even then, you have to be doing an awful lot of that to be able to justify even a 20Mb symmetric leased line let alone anything bigger.
What people don't realise is its not all about the headline speeds.... its about quality of service. Not all high speed internet connections are made of the same stuff.