I thought that too until I read this:   (You need to Login or Register

  I found some other posts about the subject too.
It talked about how you didn't have to use the MSR fuel cylinders only because, other stove brands fuel bottles would work as well.

The wild card seemed to be the Coleman Brand cylinders which are the cheapest and probably the ones they make the most of.

  Maybe they make so many in more than one plant, they have QC issues?
  Having worked in QC for a while, I know how things can vary from batch to batch or with multiple vendors.