Lol, sorry but I can't agree. It would be a gameplay mechanic if there was a button that said: Spread out. The way it is right now, it is abuse of an unintended mechanic.
(Also there is no disadvantage to it, if you do it in the earlygame while the enemy can't reach your units anyway.)
This is the defintion of abuse.
If you want more interesting gameplay mechanics, I am all for it. But don't produce them out of bugs/abuses. Because these "features", because they were unintended, miss important design "rules". The biggest would be that they are not something that is intuitiv to new (or even old) players.
If there is something that truly adds to the Gameplay, then the Devs should take it, and implement it properly. Here for example with a button, or atleast a tipp/tutorial.
(Btw, I have no Idea what the fuck was going on with the Truckcrushing. But in the end, either they were incompetend in one way or the other, or they had a secret strategy how to deal with it, but instead of showing the community the strat, they decided it wasn't good for the game anyway.)
Thank goodness most people don't think like you do, because if they did, many of the most popular competitive games of all time would have been deprived of many of their most interesting mechanics. By your logic, reversing vehicles in vCoH was "abuse" because there wasn't a button for it. See how silly that sounds? Reversing vehicles in vCoH took advantage of quirks in the vehicle AI. There were no tutorials telling you how to do it, no button to do it for you, no entry in the manual explaining it. But it became an integral part of the game because of innovative players who realized how to take advantage of the game engine in an interesting way.
Do you think the Blizzard devs realized when they implemented their unit grouping behaviours for the original Starcraft that if you have an Overlord in a group of Mutalisks and put that Overlord far from the Mutas, the game would clump the Mutas into one unit-sized group because of the separation between the units, allowing Zerg players to micro more effectively and making mass Muta strategies viable? Fuck no, the community figured out that unintended interaction on their own and ran with it, paving the way for some of the most entertaining Starcraft games in history.
Do you think the Counterstrike devs realized during development that when a player crouches, has another player jump on top of him, then stands up, he is able to boost the player up to shoot from an unorthodox angle or take a shortcut that can shave precious seconds off travel time? Hell no, but people figured it out, and started using it, and now it's a cornerstone of CS competitive play, to the point where maps these days are designed with boosting in mind.
Do you think the Starcraft 2 devs realized when they were implementing their unit movements that if you moved a group of Mutas correctly and then issued a Stop command, you could have them hover over Thors without overlapping and getting hit by the Thor's splash damage? Doubt it, but people figured out that interaction within months and changed how Mech Terran had to be played. Did players cry about "abuse"? Hell no, they adapted and adjusted. The innovation of the player base caused changes to the metagame that the developers never could have predicted. But you'll never hear anyone complaining about "abuse".
The thinking that "unintended" = "abuse" is dangerous and extremely flawed. Players are the #1 source of innovation in any game, especially those with competitive multiplayer. Developers are fosters of this creativity, not police. And the community isn't bound by what's written in a manual. Discoveries like this need to be encouraged and celebrated, because they make the game more complex and more rewarding for those who are willing to invest their time into it. If you don't care about the game, you aren't going to care about this little quirk, and you won't care that people more serious than you are using it; but if you do care about competing, you're going to see somebody using this against you and start looking for how to do it yourself, because as a competitive player efficiency is your Bible, and every extra second you can find is valuable.
You know what was "abuse"? Ghost Tank Trap spamming in vCoH. In that case, Relic issued a public statement that they would punish any player found to be exploiting this bug, and stated their intention to remove it at a later date. That right there is abuse. Throwing it around every time a player innovates is cheap and, frankly, extremely close-minded.
So please, rethink your stance. It's not healthy for CoH, and it's not healthy for competitive gaming in general. Players should be encouraged to innovate, not berated when they discover interesting interactions that aren't explicitly stated anywhere. If Relic doesn't like this, they'll patch it out, or they'll release an official statement like they did with ghost TTs. But until that happens, celebrate that there are players dedicated enough to the game you enjoy playing that they are willing to spend countless hours figuring out how the game you play can be streamlined and played at the highest possible level.
On a little side note regarding your statement that capwalking provides advantage with zero risk: even if that were true, it is a non-issue, since this mechanic is available to all players. And though I can't speak for capwalking in CoH2, I can say with certainty that every single vCoH capping order that involves capwalking is vulnerable to an aggressive opponent who can, with an aggressive build order, very easily punish your greed. I don't see how you could capwalk in a manner that grants you any noticeable advantage while at the same time eliminating all risk from an aggressive opponent; the nature of the mechanic makes that situation nearly impossible to construct.