It's often wrong too.
This is the part that drives me nuts. It is definitely useful and I've started using it alongside "googling" for answers to specific questions.
But it is not infallible and it's confidently incorrect often enough that I often have to check elsewhere to verify.
If you get your own domain, it gets difficult to be able to send anyone an email.
It has gotten really bad. Tons of small email domains get marked as spam by major email providers.