Why?

In particular when the general market of the sector is in a downturn, quite some great people are typically laid off. So, this is a, say, once-in-a-decade opportunity to hire lots of great people.

Also, if the sector is in a general bad shape, hardly anybody expects the profits to be great. So, use this opportunity to invest the available cash into speculative projects of high potential.

If the economy is in a bad shape, less people will buy your products; thus it is of lesser priority to have a product available. But since, by the previous paragraph, you invested your money into more long-term projects of high potential, you will have quite some potentially lucrative products available as soon as the economy recovers.

Only if the company is able to execute on something useful with those people. Otherwise it's a waste of money. Great for those employees, maybe.

First: finding useful projects to do with the employees is what managers are for.

Second: if you read into HN threads for the past few years, you know that quite a lot of companies are looking for great programmers to hire and claim that their inability to find such people hinders their growth. So, with the coming recession, these companies might get their desired opportunity.

It's never enough for these guys. It's a game and money is the score, they just want to run up the score.

Likewise I imagine it's soul draining to Zuck being told no by Apple. So they're probably obsessed with making their own walled garden.