> In fact, being unable to chain functions in PHP is actually my biggest beef with the language.

That's just a lie or at least a horrible misconception, depending on your intentions. Furthermore, the example line you used to illustrate this entirely made-up inability of PHP does in fact work. You can do

  return implode(', ',array_slice(explode('|',$str),-3)); 

it's valid code and it works just as expected!