Occasionally newbies will be offered the advice to use a microwave oven to heat a steam towel.

I would encourage experienced members not to recommend this henceforward.
This is an extremely dangerous practice to recommend. The risks are as follows:

1. Fire. Microwave ovens can create heats much higher than 212 almost instantaneously. While we tend to think of heating water in a vessel, a towel is not a vessel and towel and water combined have much lower density than the water. If a part of the towel dries out it can easily burst in to flames. Microwave oven manufacturers ALL warn against heating anything but food in a microwave.

2. Serious Injury. Microwaves do not heat food evenly, let alone moist fabrics. It is extremely likely that hot spots can be created in a wet towel by a microwave. Such a hot spot, applied to the face, can cause immediate 2nd degree burns leading to blisters and scarring. It is not a practice ever to be recommended.

3. Damage to the skin. We tend to think that if a little heat softens the beard, then more will soften it even better. This is simply not true. Hot water from the tap is more than hot enough to soften whiskers. No more heat is necessary, and can actually be harmful to the skin, possibly even causing premature aging. Real steam cooks things. You don't need to cook your whiskers to get them soft enough to shave.

The instructions to barbers in all of the barbering texts are excellent instructions for us, too. The towel is soaked in hot water from the tap, and is never made hot enough to cause any discomfort to the patron. This is what you should strive for with your hot towel.

Let's relegate microwaving towels to the "Three Stooges School of Barbering."

Be careful out there.