What I've seen is that salespeople are lot more fungible than veteran engineers who have a lot of knowledge of the companies system. Sales armies tend to have a lot of more junior staff too. They might not hire back the same salespeople, but they should be able to hire what they need. There will be a lot of people looking for work.

There's also reputation issues with a "hire them back later" attitude. Engineers are likely to become skeptical of recruiters from companies with a policy like that, and then you start struggling to hire anyone.

That reference was about sales employees, not engineers. I think most people realize that in larger companies the sales team and the engineering team are managed very differently, with the employees having very different expectations about the stability of their position.