Why is IE still in existence?

Now that we have Firefox, I just don't understand what good Internet Explorer does anyone. I'm sure that my problem is that I'm looking at things strictly from the perspective of a developer. But a new Gmail Notifier bug related to IE has been brought to my attention and I'm particularly annoyed about it.

If you have Gmail notifier installed on your PC, you probably are a Firefox, Opera, or Safari user. Well if someone asks you if they can check their email account on your computer, be sure to ask a couple of questions first: 1) Are you using free web-based email, and if so is it Gmail? 2) If the answer is yes, which browser are you planning to use?

These questions are important. There is apparently an existing Gmail notifier bug where if a person checks their Gmail account via Internet Explorer and instead of logging out of IE they simply close the browser, whatever gmail username and password they use for their Gmail account are captured and stored in your Gmail notifier from that time forward. It doesn't matter that you're using your own username and password you use to login to Gmail notifier, dude. The other person's messages will continue to display from now until kingdom come.

The way to get around this is to access Gmail via Internet Explorer (*shudder*) and signoff the other person's account. Afterward you should be able to access your own email via gmail notifier once you login with your username and password. Just annoying.

Source: ["On a path: technology archives"]