But it's only a website, it doesn't even runs a business after all (nobody will lose his job if PM is defaced, isn't it?)

If the system were properly compromised they could use it as a stepping stone to other sites managed by our noble hosts which would almost certainly result in them terminating their fine support of our organization. And then where would we be? No, while we are all volunteers I think most of us active participants take our roles pretty seriously and we will never knowingly do anything to allow such a thing to occur.