You are not crazy. The "everyone does it" argument should be coming from the kids, not the parents.
Google "Social Host Laws" - parents who knowingly allow kids to drink on their property, supervised or not, are liable. The penalties are severe. The judges are not interested in being told that a lot of kids drink - they know that.
Friend #1's daughter has come home drunk? How did she get home? Who drove her? How much had that person had to drink? The parents let their daughter fall asleep drunk? She called begging to be picked up before the cops came, and Mom keeps letting her go to these parties?
Friend #2 was reprimanded by the police for serving alcohol to underage kids? Does she plan to brush this off and repeat it? Does she think the police will have a casual conversation with her the next time? What's her plan when the parents of the visiting teens press charges?
They can research "adolescent brain development" on their own. The kids don't have fully developed brains until age 25. Impairing that earlier and earlier doesn't make sense.
I'm not naive. I know a lot of kids drink. My son saw it and was pretty disgusted in high school. He was disgusted in college for about a semester. Then he got tired of being the only one not drinking. He got picked up for "walking drunk" - yes, really. Weaving down the road. College public safety took him back to his dorm but wrote him up, and he had to make the difficult call to us and also inform his track coach. That straightened him out.
We had strict rules about drinking in our home. Did we give him a sip of wine or beer if he wanted it? Sure. We're Jews, and we use wine for sacramental purposes on Friday nights and holidays, and he was allowed a sip always, although we had grape juice as well. His friends came over frequently to hang out in the basement. My husband and I stopped in several times during the evening, bringing snacks and gathering trash, for the express purpose of assessing kids' conditions. Once during a college break, some college friends of one of the high school kids (meaning kids my son didn't know), showed up and came through the basement door (as all the high school kids did). We didn't know about it, and they brought alcohol. My son didn't know how to stop their drinking, and of course they all drank at college. But he did take all their keys. When my husband and I got up the next morning, there was a note slipped under our door that a bunch of kids slept over, with a list of where they were (1 on the basement couch, 1 in the living room, 2 in my son's room, 1 in the guest room, etc. Fine. But when I took one look at 2 of the kids, I realized they were hung over. My husband found a lot of beer and vodka and empties in the basement. We grounded our son. He was indignant because he thought he had done the right thing by taking their keys. We agreed with that part. But he allowed drunk kids to go to sleep with no evaluation of their condition. What if they were so drunk, they died of alcohol poisoning? What about our legal liability even though we were upstairs asleep when the kids arrived?
In your case, I would stick to your principles. I'd discuss these situations with your daughter. I WOULD have a contract with her (google them), including a code word/phrase, that you will pick her up from ANY situation where she's uncomfortable, no questions asked. Kids sometimes want to come home but don't want their friends to know that they asked, so they'll say something innocuous like "Did you buy my shampoo like I asked?" - "shampoo" is the code word meaning "come get me". The kid can then blame you for taking her home. I think these are great techniques. I told my son I was happy to be the bad guy anytime.
Remember that these parties are not just beer - there are other drugs, and many kids are pooling their prescription meds (and those of their parents) into a party pill bowl. Not a good mix.
For the purposes of discussion, I would absolutely separate out your daughter's desire to remain a virgin until marriage. There are kids who drink who don't have sex, and kids who have sex who don't drink. They may fall under the umbrella of "respecting and preserving my body" but not all kids feel this way. It may cause your friends to accuse you of not allowing your daughter to do anything at all. I think it's a BS argument, but I think it would be easier for you, and your daughter, if you held separate discussions about both of them. Her decision to not drink should not be because she's a virgin, you know?
But if your daughter overall is looking to stay healthy and not make decisions that could impair her health and safety, those are great things.
Your friends are headed for a rough time when their kids get in cars with drinkers, or throw up all over the house, or end up in the hospital, or get kicked off teams. They will get no sympathy from the authorities.