"I much prefer the idea of not cutting my dogs nails so deeply as to draw blood."
Well so do I, and I don't cut them so deeply; not deliberately at least. I don't think anyone does it deliberately. From my experience, cutting the quick is done accidentally, and many times cannot be easily prevented even when due care is taken. When cut, quicks tend to bleed without stopping as there is no skin to cover it. While the dog shouldn't bleed out, the presence of blood can cause the dog to lick the nail incessantly, and he will trail blood wherever he walks. Styptic powder (or cornstarch powder) will stop the bleeding.
For the last 11 years, I have owned a dachshund who has very long quicks. His nails grow quite fast; they don't grind down on walks like the nails of my other 2 dachshunds, and he gets very angry and fearful about getting his nails cut, especially when he sees the clipper. This is probably due an issue established by one of this three prior owners.
When I take him to the vet, they tell me they can only cut his nails back so far; his quicks are too long. They have told me the way to reduce his nail quick is to cut his nails frequently. I have been taking him to the groomer (who is less expensive than the vet) every two weeks to get his nails trimmed. They are reducing in length.
Regardless, due to his innate nervousness, he has had issues with thrusting his nail further into the clipper at the last millisecond, causing a shorter nail trim than intended, and drawing blood. Other times, bleeding just happens with my other dachshunds who have shorter nails. It's not every nail, just maybe one, once in a while.
Rather than let them bleed everywhere, the vet and/or groomer it has happened with have pressed the nail into either cornstarch powder or styptic powder to staunch the bleeding. That's why they keep it around.
"Does it cause damage or pain to a dog when cutting into the quick?"
Of course it causes them pain, otherwise my dog wouldn't be so nervous around a nail clipper, and he wouldn't yelp when he accidentally gets his quick cut into. It must be similar to when one clips their own nails too short, or worse.
"What techniques are there to help prevent cutting the quick in dog's nails?"
You can look for the white or black part, depending on the dog or the nail (my 13-year-old has one orange nail with a black interior out of all his black nails with seemingly white interiors), and not trim so close to it.
The QuickFinder is an electric nail clipper which works like a wall stud finder, sensing the quick and telling you when you've gone too far up the nail. I have been told by two individuals who have tried it that it is useless and prone to false-positives and false-negatives.
PediPaws is a Dremel-like tool, "As Seen on TV", used to scrape down the nail instead of cutting it. The flailing which ensued when I tried to introduce my dog to this rapidly spinning and whining device caused me to have to return it to the store. Neither dog I had at the time settled down to it, and when they did, the friction caused the nail to heat up fiercely. I cannot recommend it.