The way I see this idiom used is fairly consistent. $self is only returned for mutators (upon success). Thus, the expectations are clear: mutators always return $self upon success and accessors never return $self. If accessors return an object, it's known the the object is not the calling object. That, actually, is yet another reason why I prefer to have separate accessors and mutators ('name' or 'get_name' vs. 'set_name'). This clear distinction makes the expectations clear. And again, if you don't like the chained features, you don't have to use it. Chained method calls are usually an extra feature as opposed to the replacement of a feature that is already used.
I also note that you object to this idiom because it's not common. If it were a bad idiom, I would consider this to be a benefit. If it's a good idiom, then that's a negative. Which way it falls is still kind of up in the air, though. I'm glad you raised the issue.
New address of my CGI Course.
Silence is Evil (feel free to copy and distribute widely - note copyright text)