Who defines calcification and comfort zone? Be careful you don't confuse a mature stack with subject matter experts who can execute effectively as "outdated cal

Who defines calcification and comfort zone? Be careful you don't confuse a mature stack with subject matter experts who can execute effectively as "outdated calcification". I would be wary of someone who wants to hop around a lot. Are they adding tangible value to every team or disrupting things before bailing to the next team?