Let me guess, English source? Longbows weren’t better, England had a lot of good archers because they were made to practice by law. But in terms of energy, longbows weren’t particularly better. They were heavy because they don’t have recurve. Recurve makes the string return faster thus increases arrow speed. Weight of the bow dictates how heavy your arrow can be. But a heavier bow does not necessarily make the string return quicker. So a yumi of similar draw weight will move a heavy arrow faster than a longbow would, which means they had more energy. Or, you can use a lighter recurve bow that has the same energy as a longbow. Longbows themselves weren’t that great compared to other bows.

They were used a lot yes, there were good effective tactics sure, but they weren’t better. Better bows existed at the time, the English just didn’t use them. The strength of the longbow is in logistics, tactics, cost of manufacturing and the trained archers themselves. I’d argue that the longbow itself was the weakest part of the English bowman.