I think you are misunderstanding Dereck, Sanchin. When Dereck say he thinks of a block as a strike, then he means that you do not meet the attacking punch etc, head on, but instead hit it from the side. This way you are redirecting the power of the strike to the side of your body, therefore the force is not on your blocking tool. If you block with enough force then you should hurt the attacker's limb.
This in itself is not that useful, since the limb will still be usable, just bruised. When blocking kicks, the simple blocks, i.e. downward blocks and low blocks, IMO are last resorts, if you cannot evade fast enough. The best thing against kicks is evasion, or a grappling technique, things which are not implicitly a part of TKD, although I'm sure they form a part of many schools' syllabus.
I think the applications for blocks are endless; I also think that the basic method of blocking, taught at lower levels of tkd, is a bit restrictive. If I were to block, I would want to do so because it would put me in an advantageous position, not because I wanted to avoid a strike: that is what evading and guarding is for. I particularly like using blocks to change direction of a fight. An outward block with a step to the other side can open up the whole of an opponents body to counter-strikes. These "parries," where blocking is combined with movement can be very effective.
Overall though, I do not see much value in blocking as a method of escaping a strike.