My theory is: when it started being a bad thing to have any cash reserve.

With some reserve on the side, a company can survive bad times and not fire people. This is the kind of behavior employee will appreciate and make some diehard loyal.

But this available money is money not making more. So that's a bad thing these days and so the only easy variable available to survive is to remove excess workforce. It took some time for people to understand loyalty has been one-way only but now employers are reaping what they've sown.