For most saw blades there is a optimal height range of the blade due to tooth contact when cutting thin materials, and/or when you want rapid cuts. The higher the blade the less teeth would contact the material, and the higher the possible feed rate. This also depends on the spacing of the teeth on the saw.
Whenever possible, there should be a minimum of 2 teeth contacting the work piece at all times. If you try to feed it too fast in this scenario, the saw blade should gradually slow down until the motor stalls.
Lets say you are cutting something relatively thin with a low tooth count saw, it would be possible to increase the height of the blade until the thickness of the work piece can fit between two saw teeth. This creates a hazardous condition where you could feed the piece of wood fast enough to violently lock/seize the saw and damage the blade.
If too many teeth contacts the work piece and the angle is very shallow you have a increased risk of lifting the work piece off the table, usually due to feeding it too fast. This would be a kick-back risk because then the material could then twist and bind the saw blade.
The ideal saw blade height would usually be the height where 2-4 teeth are contacting the work piece at the same time during a cut.
This really only applies to the common saw blade tooth shapes, without a feed speed limiting tooth safety feature.
Some saw manufactures have a built in feed limiting tooth profile, it looks like a tail or ear behind the carbide, it is to prevent the blade from taking too big a bite out of the wood. These feed limiting tooth designs are also commonly see in chainsaw blades.
Also, if you can cut with a safety guard on, use it. Less worry about how a large exposed blade is more dangerous.