I’ve spent a good deal of my professional life arguing against using protobuffers. They’re clearly written by amateurs, unbelievably ad-hoc, mired in gotchas, tricky to compile, and solve a problem that nobody but Google really has. If these problems of protobuffers remained quarantined in serialization abstractions, my complaints would end there. But unfortunately, the bad design of protobuffers is so persuasive that these problems manage to leak their way into your code as well.
Source: Protobuffers Are Wrong, an article by Sandy Maguire.