Originally Posted by
Square Wheels
If the engineers who built these combinations don't want me to use them, why put them there?
I ride what works for me, if I cross chain, so be it.
When things wear out, I'll replace them.
How exactly would you propose to make a big-small or small-big combination available without the small-small and big-big also being present? And every cassette has two ends. No matter how many cogs you add or remove, that is still the case. Derailleurs are always going to be engineered to just barely work at the cassette edges. It is inescapable.