> Specifying version for find_package works as EXACT

You mean, it doesn't allow patch versions other than 0? That's strange, `VTKConfigVersion.cmake` for 5.8 at least looks like it does the right thing.

> Probably I'll remove version specification and will disable Viz if old VTK found.

Well, if you're going to do that, make sure to include what you've just said as a comment.