Everybody should quit using something because 0.00001% of its users are bad.
How progressive!
No, they should quit using it because Twitter refuses to do anything to moderate its users. If twitter wants to keep users, it should make sure it doesn't have a hostile space to use. If they don't do that, yes, stop using them.
Twitter is a company out to make money and the users are how it makes money. It's quite fair to say stop using their service (and providing them the stuff they need to make money) if they refuse to keep the atmosphere from being hostile.
Twitter is behind the game.
I believe China, Korea, and JP require you to use their country SSN or cellphone # to create a fricken social/online account.
I don't know why Twitter isn't doing this as well to stop the harassment.
The CEO and CTO are acting like outdated adults.
This is not the answer. And hell no I would not be giving twitter or any online service my SSN for hackers to go get. Do you realize how much a hacker can do if they get your SSN?! Neither do I want them to have my cellphone for hackers to get to be able to just call me and harass me directly through the phone (I make it a point to try to keep my number off the internet). On top of that, there are good reasons for people to want to be anonymous on the internet as well. (abusive spouses/exes that they are trying to avoid letting know where they are, governments they have to worry about finding out who just said something bad about the government...).
Nor do I think making people use their real name is the answer too. People are going to be jerks not because you know their real name (after all, it's still just a name to a random stranger) but because they feel disconnected and aren't dealing with you directly/face to face.
The answer is twitter should have better tools for users to report/block people and take reports of harassment seriously.