When talking with people who "do" BI, I listen to what they think BI is. I hear: Analysis. MIS. OLAP. Reporting warehouse. Some people have just said, "we do Oracle BI", thinking the vendor/tools are what makes BI. And my favorite, "BI is BI" (assuming everyone knows what it means?).
So I used the Internet as a research tool and I can understand why there is confusion. Websites seem to have different definitions. MIS and BI are frequently used interchangeably but Wikipedia defines MIS differently than BI. Oracle's definition is tools focused, as expected. DM Review gives a decent business focused one. Which one do you grab onto?
It is true that the BI industry is getting more complex but the message being delivered is too. When talking with potential clients (internal or external) offer a consistent story that is authentic, entertaining, and enlightening. And offer it to the right audience.
If you're technically minded, deliver a clear message on the technology, its use, and limitations. Toolset/vendor specialists would do well with presenting an open minded view to gain an audience's trust. Delivering to the business may involve telling the advantages of performing better business decisions.
The message you deliver and to whom you deliver it are important.