You talk about dragons being able to socialize...it depends what society you are refering to and also how the dragon attempting these socialization efforts. A city of dragonborn might have no problem with a dragon showing up in the local Tuesday Market to attempt to trade and sell some goods! The younger, smaller dragons would have no problem doing so.
Then there is the minion speak - again, looking at 3e for examples, a CR 15 red dragon was a 7th lvl caster. If it had a 10th lvl wizard and cleric minion, both of these had better casting and more spell choices than the dragon, but even if they joined forces, they did not have the power to take over the dragon's lair and they, as an encounter for the PCs, still didn't over shadow the BBEG dragon. Basically, in this case, the magical power necessary to ward and protect the dragon are so low scale, having minions do it does automatically mean they are powerful minions.
Moving forward to 4e. BBEG dragon can once more have minions powerful enough to do magic for him, but still be considerably weeker than the dragon powerwise.
And as for how the dragon get's it's business done:
Dragon had kobold minions. They worship him as a god and for generations have carved out a home near his lair, building traps and secret passages. The are low on the dragon's notice, but they amuse him, and again, for generations, their presence has eased his needs and brough him some wealth. Only a few have ever actually been to the dragon's lair - the tribal chief, the shaman, and the mystic are the only ones to whom the knowledge of the secret road is given. They go their monthly to pay homage to the dragon, but there is also a way the dragon can summon them, should it require them sooner (drum, gong, bellow, breath fire down a certain chamber so that smoke rises from the sacred tunnel).
The dragon, also, has challenged and dominated several orc tribes in the area. Being that the chief is the strongest and best, and being chief requires defeating the old chief in combat, the dragon had no problem doing so. It is now chief of a few orc tribes. It uses the kobolds to communicate with the orcs - it does not want the orcs knowing where it lairs, and the kobolds use all manner of long and secret tunnels, too narrow for orcs, when entering and leaving the lair. Even if the orcs tracked the kobolds back to one of these entrances, it's too small for the orcs to use and well trapped, and the passage will only take it to the kobold's lair. From there, the orcs would still need to transverse the numerous caverns inside to find the dragon, and all of them have been well trapped over the years.
The dragon then took over the hobgoblins that were setting up defenses in the ruined castle near by. This was, in fact, very easy. The dragon organized the orcs to lay siege to the place, and "negotiated" with the leader. Once again, the kobolds are the direct go-between, and there is no way the hobgoblins could muster an assault against the dragon just as the orcs could not. Besides, if the either force tried, the dragon would have the other wipe them out.
The dragon now has orc minions, hogoblin minions, and the trusted kobold minions. It's lair is gaurded by the kobolds and the traps they have set (and a few magic ones to boot, being there are a few low level casters amongst them). Between the casters of these races, it would be easy enough to have a few talisments created so that the dragon could magically communicate with the warlords of the orcs and hogoblins when direct and immediate command was needed, but mostly, it relies on kobold messengers.
Should the dragon wish to infultrate more civilized society, there are ways to go about it. Sure, the kobolds, hobgoblins, and orcs might not be able to move about freely in the city, but the wererats in the sewers can, and there are ways to garner their support. From there, humans can easily be swayed into service.
None of these minions out-shine the dragon as the BBEG and they provide all the services and protection the dragon needs. It can have them make a couple magic items it cannot, but it does not require these for use.
I think most dragons will be set up to not be these types of over-lords; I think they are being taken back to the power-house gold-hoarders that do not seek socialization and that do not want minions, and try not to influence the world around them except to collect treasure and feed (and that alone makes them dangerous and threats to the surrounding areas). But should a DM wish to make them The Threat, I don't see that magic is necessary to do so, and I don't think that if a dragon needs some minions for magically supported defenses, that that in any way implies the minions are anywhere close to the dragon's power. Yes, they can do things the dragon cannot, but that does make them inherently more powerful or more dangerous to the PCs.