First off, 780s is nothing to sneeze at and more than “good enough” as 720 is about the highest most lenders expect - anything higher is gravy.
Secondly, if you have “too little” credit, it can impact your score negatively, since there’s less ‘track record’ to go off of.
Keeping your credit card balances at 1% to 9% of total limits, with no more than 4 cards with balances, is the best.
Thanks, it does make sense after all.