As a company grows big, people go out of their way to find excuses to not collaborate and unblock others, even though helping might be the easier and quicker option.
The reason people do this is that they can hide longer in a big company and big companies are conflict averse.
It is the easiest way to demotivate A players though: people who want to work harder and get shit done. Hence the continuous churn. And the eventual lowering of the talent bar. Soon it is just B players left if you are not careful enough.
As shared in enough previous blogposts already, please please do reference checks. Not one, but multiple.
Linkedin is very easy to fake. People land a leadership role, do 1 year stint, and before they get found out move to another job.
Know many of these cases.
As usual Shreyas Doshi explains this better.