Think of it this way:
Have you ever been to a concert for a really popular band? One where there weren't seats? I'm not talking about an arena for Aerosmith, but an open venue for Flogging Molly.
What you end up with is a dispersed group of people at the back and then a sea of humanity at the front. Everyone who's near the front is pushing hard to get closer to the front. You don't move; the crowd moves. You randomly shifty slowly within the crowd. You have to use all your strength to maintain a little space to breathe. If you fall down, forget it. People are so densely packed that enthusiasts can actually
surf over the crowd!
That's a melee.
The analogy between a concert and a pitched battle became clear to me after I went to a Flogging Molly concert and then, shortly afterward, reread the Aubrey-Maturin series by Patrick O'Brian.
O'Brian was a genius of an author who managed to recreated some of the grandest naval battles of the early 19th century. As he said, [paraphrase]"As an author I find it difficult not to understate the actions I'm writing about. After all, how can one reasonably expect to recreate Nelson's action as follows 'I boarded the deck of the French 74 and, accepting her surrender, leapt across to the deck of the 54 beside her and, her colours coming down, took her captain's sword which I passed to my lieutenant who put it under his arm with the greatest
sang-froid". The action which struck it home was when O'Brian actually described the melee in which British sailors on one hand faced off against Muslim ("musselman") sailors on the other. Both sides were packed as close as could be, swords and pistols in hand, and the line of battle surged backward and forward like the motion of the sea.
Now, a D&D encounter involves just a few PCs against, say, a few dozen NPCs at once. Still, the action for a Defender is always going to be up close and personal, right in your face. This isn't a duel between heavily
duck-clothed Olympic fencers where physical contact is a no-no. We're talking the
original meaning of
corp à corp. Now it's a fencing term where the sword blades are braced against one another, nearly hilt to hilt. The actual meaning of the term means "body to body". People
shoving.
Which brings us to the original meaning of the term "melee". "A confused pushing and shoving". Like a concert. Or two Greek phalanges* face to face stabbing each other with spears. Or a few hundred sailors slashing with cutlasses**.
In the end, I can really understand someone shoving someone with a little*** effort. I can also understand how it would be somewhat rarer to hit someone's feet when you're right up in his face and all you can really see is sweat, moustache, shield, and grimace.
* The plural of "phalanx", four or five rows of spearmen with large wooden shields and heavy bronze armor.
** Technically "cutli", oddly enough. Perhaps "cutlery" would be clearer.
*** At earlier levels, a lot of effort. When you get better at shoving, it gets easier.