Truly pureblood witches are quite rare, yes. But there are plenty with a degree of magical blood, and a degree of magical talent.
[Private]
Ladies are more sensitive than we are, and they can be awfully emotional. It would be unchivalrous not to try to protect them from the more unpleasant things.
I disagree. My brother and I would have a higher chance of survival than a muggle. I'm not saying that no muggle in the entire world could ever survive a dangerous summoning, but it's more likely that two wizards would.