I think we should have a big-tent view of software and software licenses. There are good reasons to use a non-open source license. If you want to block Amazon from running your code on their servers, an open source license is not for you, and you should choose something else. There are other licenses that make source code available under more restrictive terms.

The fact that there's a clear definition for what an open source license is, and some licenses meet it and others don't, means I can make a statement like that, talking about a bunch of licenses as a group.

If it just means "licenses that make source available with whatever terms" then it's a less useful way of classifying and discussing licenses.

Most terms in the English language are fuzzy that way, but this one has a clear definition and I would like to stick with it.