I think the theoretical reason why Juggernauts is the one with the special name is Juggernauts alliances is the only neighboring starting alliance with a sound foundation towards a stable 2 way draw. Also, it includes the only power that stalemate lines affect the least, Russia.
See: http://www.diplomatic-pouch.org/Zine/S2001M/Ledder/TwoWayDraws.html
Now, if you read the article, you could see that why Turkey gets a raw deal since Vie, Bud, and Rum needs to be on the Turkey side to achieve a "good" 17/17 split.
Now, for any other player 17/17 split is the worst you can get.(You are eliminated). However, fear is a wonderful thing, and diplomats LOVE to exploit it.

I've managed to have one successful "juggernaut" alliance in 100+ games at WebDiplomacy.. it's success was probably due to the fact I had Russia, the country/player with a greater opportunity to doublecross it's partner, and that I place as high a value on loyalty as I do on winning. ( heresy to the WTA brigade )

I've had the reverse experience when I've had Turkey in juggernauts.. Continual betrayal by the blighters with Russia.

The reason that juggernauts form in the first place is because the I/A is unwilling to break up. There is such a small likelihood that either Italy or Austria are willing to ally with Turkey that Turkey is often automatically aiming for a juggernaut. Because of this, Italy and Austria are even more unlikely to break up, and players become predisposed to those sorts of alliances. Really, when it comes down to it, neither the I/A or the juggernaut are all that effective, but it also seems that whichever alliance breaks up first ends up losing to the other, so again, the effect is circular.

Turkey could try the Russian Nightmare: Turkey, Germany alliance starting year 1.
Do the Russian attack, Turkey takes Romania, and Sev. Germany walks into Warsaw, deny Sweden. Maybe promise Germany attack on Austria after Russia is gone.

Juggernaut can be a powerful alliance, but it is never unexpected, and therefore, easily seen and dealt with.

I defer to the experts. I think Germany makes a great alliance partner for Russia. But, as always, it's down to the players... and the last Russian and German alliance I was in...didn't end well for me, did it TOM ?

^^^ Probably because you value loyalty so much. ;)

I think from my point of view as Austria or Italy I approach year one cautiously that thè Jugg is an automatic especially if Russia or Turkey fails to reply. From my experience the Juggernaut has forced me into I/A - not the other way around