Because the capitalist system we have built demands constant growth. Even a very stable solidly profitable business is no good. A time comes when revenues go down and/or costs go up, that inhibits growth. The companies are so big they could weather the storm. Even if they kept all the employees and increased compensation, they would still be profitable.

But if they did that, they wouldn't be growing. The stock price would go down. The investors and executives would lose a lot of their own net worth. The executives don't have some magical button they can press to magically increase revenues instantly. Most non-labor costs also can't be cut. They don't have much control over the prices of the material goods and resources the company needs to operate. The only easy and instant action they can take is to lay people off. To simply stop spending money on work that isn't generating immediate revenues.

And what do you know, GOOG is up 4% today as of the time of this posting.