What no one has mentioned is how many "essential" skills have arisen as a result of this hack.
For instance, an everpresent threat in Starcraft is the Zerg Rush, in which a player skips building an economy to build zerglings---cheap, light, raider units--- to attack the opponent early before he has any defenses (as he, presumably, has not skipped building an economy). The zerglings are melee attackers, so holding a small choke point is an effective way of only allowing one or two zerglings to attack at a time, even if there are more (usually 6-8).
Of course, this poses a problem---if the tight spaces allow only two zerglings to attack, that's great, but the tight spaces also only allow two of your workers to fight back. Actual fighting units will slaughter worker units, so you've merely slowed your death, not prevented it.
Except! By ordering all your workers to harvest the same mineral patch, you can activate this collisionless behavior described in the article, and then fit your "super-group" of ten or so workers into small spaces---to fight the two zerglings at a time. The workers can definitely win now!
This has become a giant wall of text, but this is actually basic, easy, essential knowledge for the competitive starcraft 2 player, so it's fun to see its origins in this article.
I played Warcraft 3 and the same trick was used to surround a hero with ghouls. Since ghouls are also the unit that gathers lumber for the Undead Race, they enter a no-collision state when you right click on a tree.
This behavior was patched because it was too strong. You would just click on a tree behind the enemy hero and all your ghouls would pass through all the other units (footmen for example) and they could surround the hero and kill him. Once you kill the hero in Warcraft 3, there's no point fighting anymore :P
Another WC3 glitch is Shades (invisible scouting units) that triggered collision but you couldn't target them due to being invisible. Eventually players caught on and lined Shades up to create impassible and invisible walls.
To combat this you had to devote significant resources to units and buildings that could reveal invisible units, and eventually Blizzard patched it. Very interesting.
What your describing is called the drone drill, where you have all the workers attack at once, but this is a trick only used for dealing with the 3 pylon block (something banned in tournamnet play) as zerg. http://www.youtube.com/watch?v=M9CA9AahV1E
How the pathing trick is actually used to deal with zerglings is to have them walk ontop of the zerglings with the mineral trick and then attack, causing the workers to spread out around the unit trapping them while have the maximum amount of surface area to attack, as seen in this video. http://www.youtube.com/watch?v=X08jueOiGFk#t=140s
I wasn't aware that competitive StarCraft had ever banned anything that was intended by the game engine, and Google isn't turning up anything. Could you provide a source?
In tournament play, it isn't "banned" in a sense that you are fouled or disqualified for doing it. It's a map design and racial balance issue, which tournaments usually solve systematically by placing a neutral supply depot to prevent placing a 3rd blocking pylon. Check out [1] or [2] or search for "neutral supply depot" to find some more information.
I remember when I played Warcraft 2 (also mentioned in TFA) competitively (WC 2 wasn't meant to be played on the Internet, but we'd use Kali to simulate a LAN over the Internet and then we'd use trust-based ranking websites)...
The "build" was to put two barracks (or any other building) just touching each other by a corner and you'd then put three units in a special formation: then any rush would result in the rusher only being able to attack with one unit while you'd have three units hitting the attacker.
Needless to say rushes weren't a big part of the game in WC2 ; )
For instance, an everpresent threat in Starcraft is the Zerg Rush, in which a player skips building an economy to build zerglings---cheap, light, raider units--- to attack the opponent early before he has any defenses (as he, presumably, has not skipped building an economy). The zerglings are melee attackers, so holding a small choke point is an effective way of only allowing one or two zerglings to attack at a time, even if there are more (usually 6-8).
Of course, this poses a problem---if the tight spaces allow only two zerglings to attack, that's great, but the tight spaces also only allow two of your workers to fight back. Actual fighting units will slaughter worker units, so you've merely slowed your death, not prevented it.
Except! By ordering all your workers to harvest the same mineral patch, you can activate this collisionless behavior described in the article, and then fit your "super-group" of ten or so workers into small spaces---to fight the two zerglings at a time. The workers can definitely win now!
This has become a giant wall of text, but this is actually basic, easy, essential knowledge for the competitive starcraft 2 player, so it's fun to see its origins in this article.