Why do (most) strobes use Xenon flashtubes instead of LEDs?

[encrustingacro]

I remember hearing from a Backscatter video not to use LED video lights with a strobe/burst function for underwater photography. They stated the LED ones don't use capacitors which means the flash time isn't fast enough, and the LED isn't as bright. Well, why don't LED strobe manufacturers use capacitors, and aren't LEDs brighter per watt of energy used? Is it because the capacitor might overload the LED, destroying it, or that LEDs with the same brightness as a Xenon flashtube are too expensive?