Absolutely true, Paul. Or you could take the approach that Members of Parliament do and assume that for every letter of complaint they get this represents a hundred/thousand unexpressed opinions … ? So (just playing) we could say that there are more than 20 failures that I have yet to find on the internet – so double this to 40 (conservative estimate) then multiply by a factor of say a conservative 500 = 20,000 potentially with this fault. One website reports 80 million Canon EF lenses sold until 2012. The 24–105 IS was introduced in 2005 so maybe they made a generous quarter million. So this would represent a failure rate of (roughly) one in ten, to date.
I know, lots of assumptions. And I'm probably totally wrong. However, when my 5D's mirror took a surprise excursion, searching the internet did reveal a large number of other owners who had experienced the same problem – and Canon did own up to that one !
I don't have a dog in this fight, but it should be pointed out that Canon will still repair, without charge, original 5D mirrors (nothing else on one, mind you). Switch to Nikon if you want for IQ, ergonomics, lens availability, etc, but if you do so for reasons of reliablity or service, recent experience suggests you'll be out of the frying pan & into the fire.