Another point to consider is how many people have more than 2 or three lenses? If you can get the lenses you want then I think the sheer number available is a moot point.
Ah, but the point is this. If you're just starting out you don't know what you need yet. So you get one lens, maybe two. Now you're a year down the road ready to invest in that third lens. The whole point of lens selection is: is that ONE lens you need available.
If you happen to be a person that desires/needs a 70-200 2.8 lens that lens isn't there for you to buy. So it's not a matter of needing to own 50 lenses - just a matter of having the lens you need, AND having a selection at different price points.