A Steam account can be hacked, but a user can also get his or her own account banned.
A Valve employee says this feature is coming in a beta update to SteamOS, but only for those that buy or sell on the site.
SteamOS users will need to do the following: open the settings menu.
Select Account Management.
Click on Accounts.
Select the Account Settings tab.
Scroll down and select Manage Accounts.
Under Your Steam Account, select your Steam account and click the link to ban it.
The ban is permanent, and you will be unable to log into the site or buy and sell on Steam in the future.
Valve will not be making any changes to this feature, and users will still be able to buy and trade on Steam if they so choose.
It is unclear when Valve plans to make this change, and if this feature will be available on other platforms.