Because it's combination of: debounce settings (lower button lag = higher risk of double clicking), environmental humidity (low humidity causes static buildup and doubleclicking), and switches ratings have almost nothing to do with their bounce properties, apparently.

Are Omron switches good for drag clicking?

The Glorious Model O Gaming Mouse is another strong contender for the title of the best mouse for drag clicking, and it's easy to see why. It offers just about everything that you could need. A matte textured surface and durable Omron mechanical switches rated for 20 million clicks.

Can optical switches double click?

No, razer mice use optical switches, which means they cant doubleclick. RIP to you and your butterfly clicking. This is completely false. This is completely false.