(Love your avatar Xythex.) :)
It is very possible to hack EQ accounts even without folks sharing out passwords, which is of course a very bad idea. Even if someone is your 'best friend', that person may share the password with his/her 'best friend', etc. Also keep in mind that friends usually write down shared passwords or keep them in an easily-found text file on their PC's. Now if a little brother, brother's friend, or somesuch finds that information...oopsie. But aside from the easy ways to steal account information, there are other ways that are not so simple. Brute force password crackers are rare, but they do exist. Just as MQ can be used along with EQ to cheat the game, a very specialized brute force cracker program could be written to attack character account logins. EQ has many safeguards against such, but they do exist. Sometimes even good guessing can reveal a person's password.
I will list some preventive measures--mostly standard good security practices--and encourage others to add to this list.
1. NEVER give your account info to ANYONE, friend or not, unless you are fully prepared to lose every character and item on that account. If you have buff boxes that you want to share, that's one thing, but just be prepared for someone to eventually clean you out or otherwise misuse that account.
2. CHANGE your account info at least every third month or so. This is especially important if you have made the mistake of sharing the info with anyone. Switch passwords at the very least!
3. DO NOT use any part of any of your character's names as a login or password. Hackers start out by trying character names as logins and/or passwords.
4. DO NOT use actual words, misspelled or otherwise, as passwords. In fact, use nothing at all that has any meaning for you or is 'easy to remember'. If it's easy to remember, it's easy to guess. Things like your phone number or your mother's maiden name are surprisingly easy to discover. Use nonsense strings of text AND numbers. For best security, mix in caps and non-caps with numbers and symbols. This defeats 99% of all brute force crackers. Your password should look something like this: 2x45IUz#)
5. If you record your login/password info (which you'd almost have to if it's a nonsense string) put it someplace SAFE, especially if you have a little brother, sister, roommate, son, daughter, nephew, niece, family dog or gerbil that has access to your computer. If it's stored on your PC, put it somewhere besides 'My Documents' and name it something misleading, like "grocery list.doc" If it's on a piece of paper, hide the darn thing well and just put the password on it, not an explanation like "EQ PASSWORD = *erTY239x$"
6. If you ARE hacked, immediately report it and change your login/password information. That's usually shutting the barn doors after the horses get out, but you might as well do it to keep the hacker from doing further mischief. Odds are, your account will be cancelled if it is compromised and you'll have to start everything over. But it is possible with a bit of detective work to track down the hacker simply by finding out who was given all your gear and plat. You may not get anything back, but the hacker will be banned and lose all the gear too. Often times, the hacker will be some sleazy little freak trying to make RL cash off your gear anyway, so you're hitting him where it hurts...in the wallet.
7. Constantly update your antivirus software and spyware scanners. Spybot Search and Destroy combined with Hijack This and Norton Antivirus is my preferred security suite, along with an Nvidia firewall. If you keep these programs updated with the latest patches and definitions, it will be extremely hard for keyloggers and trojans to get installed on your PC. This will not only keep your EQ account information safe, but ALL information that has been entered into your PC.
In the end, I'd have to agree that 90% of all hacked accounts aren't really hacked in the traditional sense, but merely an example of someone being extremely careless with their account information. With a little extra effort though, you can really protect yourself from this sort of theft. Hope this helps. :)