The bad thing about method chaining is debugging a line that's in a chain. You can step INTO a line, but if you don't know which part of the chain is busted before hand, you have a lot of chaining in and out. If one does something like...
in reply to Method Chaining and Accessors
You're more likely to get an easier to diagnose report should something go odd. Also, it won't matter if y(), z() or moo() returned anything at all. It's a minor quibble that becomes defensive programming.