Seriously - 20 samples per second? Engineers put men on the moon with slide rules. You just don't need the kind of accuracy being touted these days.

The sensors used are not that well-behaved. Not very linear, noisy, etc. So you might actually need that 20Hz to produce a proper value at 1Hz. Many noisy measurements average
out as one pretty good measurement. This has even been proven, by letting 1000 people guess the number of balls in a fish bowl. The average was spot-on.

Also, fast sampling allows one to do all kinds of filtering in software which required analogue filters in the past.