I've never had a server where every op restricts everyone else's building areas with their own op blocks, but only for their own buildings to prevent them getting griefed. Though I'm an op on at least one server, I don't really use that block when constructing stuff, but only for outlining main things (like underground rooms or bridges) to prevent griefers drilling through it and possibly flooding the room(s). (I wouldn't use the op block for building anyway; it would look ugly.)
I also disagree with ops having their own library of permanent blocks. There's really no need for that. It's basically cheating!