Voyager EMH
Slipper Wearing Plucker of Pheasants
This may be true for the audience you are addressing.Of course. Thats the nature of averages.
And would agree, mids who become low single digit, probably have the speed to begin with.
There was in the past though, a tendency to view speed/length as more of a you-have-what-you-have fixed thing. Now its clear that the majority can probably gain 5-10mph club head speed. And thats a useful difference.
Also, probably influenced by old litterature, and those of use who remember using wooden woods, distance would have been regarded as less limiting a factor in ones golfing potential in the past. Now it is clear, from better data, and the step change in equipment 25ish years ago, that distance is the unavoidable key. You will not reach low singles if you only hit it 200yds. You probably play off low singles or better, if you can hit it 290, almost no matter what else the rest of your game.
Wild speculation on my part coming up:
Take the top 50 or 150 tour pros in the world, bring them to my club, no club in the bag longer than their 200 yard club, get them to play 20 rounds. Very few, if any, would end up with a handicap index above 4. Several would get a + handicap. Their overall ability and experience would get them plenty of birdies on the five par 3s and the three par 5s.