Originally Posted by B. Carfree

They relieve pressure under the sit bones by having the perineum take more load than it is designed for. For riders who have been around the block a time or two, it's no big deal since we tend to put very little pressure on the saddle anyway (more power means more of the load goes into the pedals and correspondingly less into the saddle). However, sometimes one just wants to spin away at low power. With a Brooks, that can be a recipe for vascular and/or nerve damage to an area that many of us would like to keep fully functional.

That said, if your miles are low, you may well be able to ride anything without worry. My wife uses leather saddles for her town bikes, but neither of us would ever dream of going back to them for the longer rides we do.