But, that is first time I ever saw a site use the expression "Powered by Free Software"
It is a good thing to boost awareness of free software. However, that expression has more than one possible meaning. It could mean that *all* the software running the server is free, or it could mean that only *some* of the software running the server is free. One cannot tell which.
We should encourage people to say things which are unambiguous about this.