Spot versus Flood in LED Lights

I am very new to LED lights. I just recently purchased a Olight M20 R2 as my first LED light. One thing I seem to notice when looking at many many different lights and reviews is that very few LED lights offer an adjustable beam from spot to flood. Why is this? Is there something about how an LED light is made or how it functions that makes this more difficult or more expensive? Does the method used to accomplish this with an incandescent light not work with an LED light?

Usually because it's not necessary: as you have probably noticed, the beam from an LED light tends to have a combination of both - a bright central hotspot surrounded by a much wider spillbeam.

The small size of the light emitting region in LEDs means that you can get very smooth beam profiles with few artifacts - effectively you have a point source which can be placed in the correct position relative to the reflector.

If you still have an old M@gLite you might want to compare the beam to that of your M20 - in addition to it seeming very faint and yellow you'll probably be shocked at how non-uniform the M@glite beam is. Horrible, ringy and probably with a great big doughnut hole in the middle. This is an inevitable consequence of having an extended source (i.e. the filament in the bulb): not all of the light emitting region can be at the focal point of the reflector.

The variable focus of these older lights was in part a way of covering up the horrible beam quality - at least you could adjust it to get a more or less worse effect. With LEDs this is no longer necessary.