Yes, they are designed as an efficient construction material meant to be maneuvered by hand under normal human power, a feat they excel at, as evidenced by their ubiquitous proliferation.
But what if you're not a normal human? What if you work in an office all day and have the equivalent forearm strength of a small child? Or what if you just don't really want to torque up your wrist and elbows hauling big heavy things because it would interfere with your tennis swing or the fluidity of your interpretive dance expressions? Or what if you're an OCD engineer and simply must devise the most efficient load transfer mechanism throughout your body for every single item you ever pick up? Or what if you're lazy?
Well, gather around misfits, and hear tell of how you, too, can be of some marginal use on a construction site, despite your crippling dainty or schizoid mannerisms.
Step 1: Think.
Man is a tool-making creature, not because he is particularly noble, but because he is lazy, and would prefer it if the laws of physics would do his work for him, or at least interfere with his desires as little as possible.
One of those laws is Gravity. More often than not, Man finds himself diametrically opposed to this law. He is at odds with it all day long, and though he appreciates its purpose, he will try to circumvent it at every opportunity. But in order to do this, he needs to know a little about it, for "Knowing is half the battle." **
So he sits down in a comfortable chair (See? Already he's giving Gravity the proverbial finger, because his legs sure as smack don't want to carry all this weight around) and says to himself:
"Gravity moves in a straight line, and an object supported any angle apart from directly up and down will incur additional resistance, particularly at those points at which departure from vertical begin." Or "Heavy things held out make arms and hands hurt."
In order carry a concrete block normally, Man would grip the block from the side, offsetting the block's loading axis from its center to the edge. Now, the block is a tightwad and will follow Nature's statutes and by-laws to a T, so when it senses it's being picked up off the prescribed axis, it will contort itself until it has re-righted itself with Gravity's regulations. As it angles itself, it becomes more inconvenient for Man to hold. He must angle his wrist and elbows to counter-compensate for the block's adjustment and tighten his grip to prevent the block from slipping. All of this because he marginally infringed upon Gravity's "straight down" clause.
But what if there was a way to keep everything in line? What if there was a way to grasp the block from straight above? It would mean eliminating all ancillary stresses from the equation, rendering the block much easier to maneuver... but how?
Now, bear in mind, Man is not a creature of infinite intelligence, and thinking takes effort, so he employs another strategy to hold information for him and minimize his own exertion - he draws. And once an image mysteriously appears that makes some modicum or sense, he musters up enough strength to get out of his chair and get to work.
* This person's name was Apollo Creed. He was a genius who hospitalized an Italian with a below-average IQ in a fist-fight. Later, he lost to that individual, but while his opponent came close to squandering all of his new-found wealth, Apollo managed to retain buckets and buckets of money, because he was smart.
** Quote from another one of history's most pivotal personalities.