MultiBindings are NOT useless in MVVM
Lately I have been detecting a growing sentiment that any use of MultiBinding is poor practice in MVVM (this thread on WPF disciples for example). However, I think people who say you should never use MultiBinding are missing its point. It is probably better to make a single binding to a FullName property than to multi bind to FirstName and LastName and then convert it into a full name. But there is still a scenario that demands the use of MultiBinding: bindings that need to update when more than one UI property changes. MultiBindings are not just used for passing more information to the converter, they also specify when the value needs to be updated and call the converter again. This is a much more important feature and it requires MultiBinding.
Just googling - found your post.
Wouldn’t you think that if a property value was dependent on the value of several others, that it deserves a place on the VM in its own right (and as such, is tested)?