Spamming seems like such a negative word though, it fits very well in an article bashing it. If I'm going to promote it, I need to make a word that shows it in a more positive light.
Let's call it Awesoming.
Awesoming, as defined by me, is fielding multiple units with identical or very similar equipment. This is done primarily to make writing army lists easier as you can just copy+paste to save time or put 'x'x in front of something (or behind, in which case, you reverse them). The first x is a variable that represents a number while the second x represents the word "times" as in multiplication. I could use a different letter to avoid confusion, but fuck you I need to make sure you are paying attention.
Another advantage of awesoming is redundancy. Taking multiple similar units means that instead of having just one threat, you have many. Relying on just one unit to do a particular job is a bad idea because once that unit is dead, you have nothing to do said job. Everyone knows the dice can be pricks, so taking multiples of your important unit (or multiple units that do a similar job) will ensure that if one unit decides to spontaneously combust you have backups.
One important part of making a competitive list is being able to handle multiple threats, from Land Raider awesoming to hordes of dudes or anything in between. Having a single unit dedicated to busting up AV14 is all well and good until your opponent figures out you have nothing else to stop his AV14, picks it off and runs roughshod over your army. Having 2 units to handle AV14 means he has to kill 2 units, and so on. Making it harder for your opponent to remove your counters to his units is crucial in a successful competitive army.
Taking different units with varying effectiveness against certain targets in an attempt to confuse your opponent is just fucking stupid. I'm sorry. If you have a unit with meltaguns, a unit with a lascannon, and a unit with missile launchers stacked up against my Land Raider, I would have to be an idiot not to pick out the major threat first, the meltas. A Lascannon is very unlikely to pop AV14 and missile launchers won't do much beyond scratching the paint. If you had 3 units with meltas against my Land Raider, I would need to knock out all 3 units because each one is likely to destroy my tank.
And it's not enough just to awesome one unit. Loading up on meltas to the exclusion of all else, taking nothing but shoota boyz, or fielding Razorbacks out the ass is not a good idea. Sure I won't be able to stop your meltas, but if I'm running horde Orks I could give a shit about meltas, right?
You have to have flexibility. You need your units to be capable of performing multiple roles, so if you run across a one-trick pony list you don't have units that are useless. The best units to awesome are units that do just this. Not only do you have redundancy, they also perform multiple roles. Imperial Guard Veterans in Chimeras are a perfect example. For 155 points you get 3 meltaguns at BS4, an AV12/10/10 tank with multi-laser and heavy flamer, and a scoring unit. They can pop heavy armor, stick wounds on something from afar or kinda threaten light armor, BBQ hordes, do all the stuff tanks do (shock, block LoS, push units around), and they score. This is a flexible unit, not a Devastator Squad with 4 missile launchers. Can they move? No. Do they score? No. Do they scare heavy armor? No. They can do everything from kill off Rhinos to stick wounds on clumped up hordes. Capable, but not worth awesoming.
And then we run into the morality issue, which shouldn't be an issue at all. Why are only certain units awesomed? Because they're underpriced, overpowered, or abusive? Nope, because they fit this type of build well. Multiple units with multiple roles multiply the effectiveness of each unit being awesomed. Taking 1 unit of meltaVets is good, taking 4 is better because each unit can do a ton of different things and support one another. Is it wrong to have redundant units so you don't rely on 1 unit?
Is awesoming abusive? No, it's part of the game. That's just like saying taking AV14 is abusive. You can't awesome just any unit, it takes experience to determine which units are worth awesoming, how much to awesome, how to use them well, and what else to field in addition to your awesome. Crying cheese, abuse, overpowered, blah, blah, blah is the cry of the scrub. If you want to impose restrictions on yourself out of some deluded moral superiority, go right ahead, but if you want to go to a competitive setting without using all the tools available, you can't cry foul when somebody who doesn't feel like straigh-jacketing themself stomps you. In a friendly setting, it's fine to impose restrictions to make things interesting, so long as both players are cool with it life is good.
Some people think that awesoming is a shortcut for weak players or that it is indicative of the netlisting problem in 40k. Well, some people are idiots. It's not enough just to take good units, awesome them, and call it a day. You have to know how to use your awesomed units and how to build an army around them. Any chump can copy a list off of the great blogs he follows like Blackjack&Hookers (wink), but will that be enough to be successful. Maybe against shitty local lists or other inexperienced or bad players with worse armies, but not against an experienced player. This isn't some dumbass card game, playing 40k competitively requires skill and skill only comes from practice. Learn the rules, learn the armies, learn how the armies operate within the rules, and figure out just what you need to bring and how to use it to get the win. The best way to do this is practice, and read the great tactical articles shown on your favorite blogs like Blackjack&Hookers (wink).
So that's awesoming in a nutshell. It's a nice way to tighten up your list, causes problems for your opponent, and is a great way to help improve people's games.