One of a kind -- An HR issue at work?

Companies that harp about diversity have forgotten that diversity is much more than the male-female ratio. An extremely irritating trend is visible these days. At least in the IT world. Here is why HR needs to manage the allocation of people from similar linguistic (and cultural) backgrounds across teams.
I've nothing against any language, religion, state or culture. But I've seen numerous instances of technical teams and client accounts facing people & hence delivery issues cause of allowing too many of the same kind in the same team. From what i observed, here is how the problem develops:
1. The first set of people form a pretty close knit group leaving out a few of the other kind.
2. They makes a lot of referrals and bring more of their own kind. Most with dubious records.
3. They make sure that they collectively hide the shoddy quality of work, low utilization and countless hours spent in avoiding work. All cause they are friends, brothers. Whatever! The lazy ones (generally agressive and frequent job changers) go about surviving with the help of the few good ones (busy, quiet, loyal). I've seen appeasements ranging from booze to bootlicking.
4. A very few of them are actually productive but a coupla years down the line the entire group mysteriously clears almost all professional certifications. ITIL or PMP, just bring it on. Work has already started suffering. Missed deadlines, SLA breach and so on. Such "things" are "managed". Numbers massaged to turn reds to greens.
5. A few good ones move up pulling a few of the lazy lot of their own kind. The other kind do not figure in the list or even if they do, its cause one of the lazy kinds has quit. (He is sure to be frustrated and is going to quit sooner than later!)
6. The business keeps growing and the lazy lot move up in the order to survive just by giving instructions and not really doing much else.
7. The entire middle management is actually a mis-management by now. People with zero maturity, zilch potential and fake experience are Project Managers and above. The whole account, company & the client is living in a make believe world.
8. Teams are frustrated cause the deserving ones aren't being appreciated and rewarded. A few good ones are overworked for one reason or the other with no respite in sight. Their leaders do not have the capability to understand and resolve the real issues.
9. The good ones finally find another job leaving only the lazy lot in the technical teams & middle management at onshore & offshore.
10. The account head by now has too many problems to handle and is too busy or he simply chooses to turn a blind eye and bides his time. Numbers are massaged as always and the business flourishes.

The story has a happy ending mostly with the lazy lot going on to form companies of their own! (That may put livelihoods of thousands at risk.)

I've seen this happen. Maynot always be at a scale I mentioned. But who says good always wins?