Isn't it obvious? Senior or long-term employees that leave take with them tombs of process/folk-knowledge with them. They take the answers of "who do you talk t

Isn't it obvious? Senior or long-term employees that leave take with them tombs of process/folk-knowledge with them. They take the answers of "who do you talk to in what team to get x done?" and "how best do you navigate this team and their hot-headed manager to get what you need?" etc. etc. Documentation is helpful but the intangibles that come and accrue to just someone or someones who have been in the trenches for years and years can't be documented and when they leave it can be fatal at least for a team/unit. Add to that the onboarding cost and the cost of hiring: take in-house or (worse) external recruiters and their salaries/commissions, add to that senior engineers taking time to interview candidates and both prep for the interview (hopefully) and then write up detailed notes afterwards -- count not only their time doing this but their time NOT mentoring a junior engineer or working on something else during that day (yes this might sound like double counting but senior engineers really do make 1+1=3 so pulling them off something is extra costly imo), and then add the expense of the employee being hired, all their gear that they'll need, and then the 3-6 months until their productive and all the help/training they'll need to get to productivity AND THEN imagine all that and then person leaves after 6 months to a year: how much does that cost? now multiply that by your attrition rate... it gets hella costly.