<<Correct me if I am wrong, but as I understand, the triple- and quad-tip
plugs still only fire to one tip at a time, not all at the same time.>>

IF you read what I said "The four tips ensures firing of the plug."  NOT all four tips fire.  I know and I think it was discussed in another post.  Only one electrode actually fires. The current takes the easiest path to ground and four electrodes means longer life.

Four paths to ground are better than three, right?

Robert