I'm obviously in the minority here but here's one data point for you. When I moved off-grid, I had three choices for internet, broadband off cell towers, broadband off satellite or no internet. Seems to me that power lines and phone lines tend to be in the same general vicinities and that a phone line strung a mile down someone's driveway with no power line would be the exception, rather than the rule. But perhaps my experience is different than others.
I think if you took a poll of the people actually using dialup or other similarly slow internet to access this site, you might find that they are not physically limited to slow speed as much as they are financially limited.
Just my 2 cents.