People have been integrating web services with excel for two decades. Previously you had to write a C XLL to do it properly, but COM add-ins have been supported

People have been integrating web services with excel for two decades. Previously you had to write a C XLL to do it properly, but COM add-ins have been supported for a long time, although have oddities, and now you can load .net assemblies into excel. You can use kerberos baked into windows for authentication, or just use http basic auth, and control access to data sets just like any other thing. So I guess, I'm confused by the article because a lot of the claims about how you have to do things in excel don't seem to be quite right.