I think its easy to criticise but people have been reporting good success with this type of strategy.
Here is a post from a few years ago saying something similar.
From A to Z – the 7 steps of building profitable web sites | OBannons Leap
While here is Jown Chows view..
Big Sites Rules, Small Sites Drool | John Chow dot Com
which is similar to this one.
SEOmoz | Five Reasons Why It's Better to be Big & Popular than Small & Niche
I think the point is that there are different ways to make good money by building out your domains. Not all of domain names can be developed with a minisite because you have to rank well in Google to see any return. However, part of the reason I posted the link here is that we have been discussing how to make a £1.00 a week
http://www.acorndomains.co.uk/mini-s...rn-1-week.html
......and this is probably the nearest to a working formula for domainers that we are likely to find.