Why “Big head and little arms”?

Sometimes a project manager can feel like a T-Rex: a big head with a lot of knowledge and experience, but with arms that are too little to actually get the job done.

And to be honest - a Project Manager can feel a bit like a TRex these days - on the brink of extinction, new creatures are standing in the wings ready to replace the "TRex-projectmanagers": Scrum masters, Product Owners, Release Train Engineers, Solution Train Engineerings, Epic Owners, Lean Portfolo Manager....
"Big Head and little arms" is not a chronological blog, but more a blog with some selected experiences meant as an inspiration for other R&D managers.