Hi - been playing for many years now. One of the most common mistakes I see beginners make is to pay too much attention to this rule, especially when bending strings. If you look at videos of the greats like Hendrix, SRV, Clapton EVH etc, you'll see they usually use their ring finger when bending, not the pinky. Why? Because it's stronger. Here's an interesting quote from Joe Satriani in his column in this month's Guitar Player mag.

Q:"... some players are taught to bend with their fourth finger in that situation" (unison bends on first and second strings)

Satriani: "You can do that - that approach fits the whole 'one finger per fret' philosophy some people take - but just looking at the hand, you can see that the 3rd finger is bigger and stronger then the 4th. Plus, it's connected to more muscle and more of the hand, and is in a better spot to create that fulcrum needed for bending and vibrato. There aren't and shouldn't be any rules as to which fingers to use when - every human hand is different - but I generally only use the 4th finger when no other finger will do."
Well i agree with that, i personally dont use my pinky to bend and if i do its with the support of all other 3 fingers. I am however a fan of the 1 finger per fret when it comes to running through scales and playing riffs..........i just think its good practice and it simplifies it instead of running over the fretboard with just 2 fingers. Why have a pinky if your not going to use it.
i agree, bendings with the pinky are hard because it lacks strength and accuracy (to hold the bending steady)
but i think a far worse mistake a beginner can make is to not use the pinky at all und let it fall behind the other fingers
i think the rule is great for beginner's to build up finger strenght and independncy, and drop the rule later on and play with whats best/easiest
By being real anal about this rule I can bend pretty well with my pinky, it's an excellent rule to strengthen the little guy as you can see many players kind of overlook it. It also has made ho/po's a breeze with it.

I think neglect is the key here, not to get too accustomed to one way of doing it. You lucky enough you got a pinky that works-- use it!
I bend with whichever finger is nearest, rather than having to reposition my whole hand to bend.
Most new players have weak pinkies, so they avoid using the pinky. They should be doing the opposite. Once the pinky is strengthened up some, you can bend with any finger that feels comfortable.

Ain't no rules, just good ideas and bad ideas.
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I don't necessarily avoid using it, but most often when I'm playing I tend to use my ring for large bends, especially the hold and release type, because I've noticed I can "get ahold" of the string better.

I use my pinky more for vibrato, because with the smaller surface area it leaves more room to get that note "moving". It hurts like hell after a while, but getting that solid vibrato makes it well worth it
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Dimebag used his pinky a lot for some of those amzingly wide spreads he did. There's a great video on YouTube from some guitar clinic he did in Arlington TX, it shows closeups of the Cowboys solo, lots of pinky work there. But it seems he does most of the bends with his ring or other fingers, not pinky.