If I work with 100-300 people over a 5 years period the number of new companies would be in the 10,000+ range. The growth has been crazy.
Those reference checks target companies on your resume not positions you didn't accept.
This is happening more often because of long hiring cycles where candidates invest so much time in multiple rounds that offers and deadlines often do not align. I use to be able to target one company and find out quickly (one interview, maybe a test) if there was an offer. It literally takes 4-8 rounds where any one round can knock you out.
Having said that I've never pulled my acceptance. Once time I quit after the first day.. One small room that was so crowded it wasn't going to work (the interview happened elsewhere). The first few months are a trial for both parties.
I would like to believe that your professional growth outpaces the growth of the industry. For example, if in year 1 you knew 10 other engineers, hopefully by year 10 you met many more - to the point that the ratio is higher than the growth of the industry in that same time period.
> I have never run into anyone I ever worked with in any other company.
That's not the question. The question is: "did anyone at your new company take a minute to search your social media accounts to find out if they have any shared connections?" Hint: if you got the job, it doesn't matter. But what about all the other times when you didn't get the job? You would have no way of finding out. On that note:
"71% of Hiring Decision-Makers Agree Social Media is Effective for Screening Applicants" [0]
> why doesn't this great candidate (you wanted to hire them) decide to back out. What is wrong with this manager/team
Nope, if a candidate accepts and backs out a week before their start date (as explained by the OP), that's 100% on them.
> if you are successful impacting their career they can personally sue and take everything you own.
Just because it's a corporate best practice to respond to official employment references in such a way to minimize the risk of lawsuits, it in no way means that 1) confidential backchannel references are done the same way, and 2) that speaking the truth violates defamation laws. For that to be true, you would have to 1) tell a lie, 2) know that it was a lie, and 3) for that lie to cause damages. I have never done such a thing and will never do - but I have spoken the truth while giving backchannel references. Two very different things.
https://www.prweb.com/releases/71_of_hiring_decision_makers_...