https://www.youtube.com/watch?v=d4b5IclFJ8Q
Completely ignores that the best known historical HA's (parthians, huns, mongols) also had sizeable cataphract style heavy horse that worked in conjunction with them. And even what he calls light cav would charge to break appart infantry formations after tiring them out, then run them down. They weren't forced to use the compound bow exlusively.
And I'd posit that the biggest advantage of all mounted armies such as the mongols was it's amazing strategic advantage, of moving tens and even hundreds of thousands of men gigantic distances in a very small timeframe.