The following link may help explain better than I can:
http://www.stanford.edu/~voloshin/lhowwhy.html
Second to last paragraph says: "the simulation data supports our claim that HP is the important factor in car acceleration."
You are probably right about less friction at lower RPM, but the question was about acceleration, not fuel efficiency.
I don't think a CVT makes any difference - let's say I have a 5 speed box and for arguments sake, lets say it has a special shift/clutch system that gives me totally lossless gear changes (full power applied all the time during the change)..... now lets say it's a 6 speed, or 7 speed or 20 speed? In practice, when I have enough gears, with close enough ratios, it's that same as a CVT.