A reflector redirects to the front close to all the side output of an led, crossing the lens and attaining a very high emitter light output extraction ratio.
An aspheric lens can only focus the led output which crosses it. When in flood, with the lens closest to the emitter, still a certain angle of emitter side output is lost which, despite output being less intense at high angles, this is more than compensated by its total area. I'll make use of a couple not so self-explanatory, but clear enough, images:
https://seos-project.eu/laser-rs/laser-rs-c03-s02-p02.html
What this means is that an SK68 or SK98 are only outputting ≈70% or little more if lucky of the total emitter lumens when in flood. Then, as you zoom and increase the lens distance to the emitter, the output diminishes even further, probably down to ≈30% or less of the total output when fully in spot or zoomed.
So, the emitter light output extraction ratio in a small lens zoom flashlight ranges from bearable down to @#$%. On the positive side of things, nothing beats the evenness of the blanket of light coming out of a zoomie as a flooder; this means they're the best for close range lighting. 