Yes, I think that's what they're talking about.
But the difference would be if you're having very slow speeds and you're waiting a while for pages to load and videos to buffer.
If you have decent speed then it will not make any difference if you're pulling 6-7mpbs or you're pulling 100mbps.
The pages and videos will load about the same time.
You can only do so much with 125mpbs on a cellphone unless you're tethering to other devices that are downloading big files.
That's a really good point. It probably matters for someone jumping to broadband/LTE speed from something like DSL/2G speed. I agree, I'd suspect you'd see no change in usage for someone going from 7MB down to 100...especially on a smartphone.