Oklahoma does not rain gently. A spring storm can drop more water in twenty minutes than a mild climate sees in a week, and undersized gutters simply give up. Water sheets over the front edge, lands at the foundation, and starts a much more expensive problem than the gutters would have cost.
Sizing matters more here than almost anywhere. Wider gutters, oversized downspouts, more outlets on long runs, and a real slope so water moves instead of sitting. That is the difference between a gutter system that works in a cloudburst and one that only works in a drizzle.