Dave

28 Years and counting, and Oda still hasn't learned how to properly pace his supposed Magnum Opus...

In all, you can skip years worth of manga chapters and/or anime episodes (even non-filler) and hardly miss anything crucial at all...

And the thing is, i don't even dislike One Piece, it's just the truth.

So, in short:

Oda is pretty lazy with certain story elements, while simultaneously being prone to overcomplicate things for both himself and the fans...

That makes sense.

As mentioned by others:

Toriyama really disliked drawing Cell, that's the real reason he's not in DBS.

Also, no, Cell Max definitely doesn't count, that's Cell's equivalent to Bio Broly....