The thing is, Dropbox is done (as in feature complete). Like when the construction of a building completes, many people are "laid off" because they aren’t needed anymore. Yeah, you need to keep some people around for things like maintaining the building, but not to the scale of the original workforce required to build it.

It is "good" that the excess labour is freed up to go work on the next "building". What may not be good is that the workers didn't think to associate with each other like construction workers do. Construction, being a much more mature industry, typically keeps a clear separation between the workers and the building so that then construction is done the entire excess group of people can be lifted on to the next project instead of all going their separate ways.

Software will undoubtedly go that way eventually. But it is, in the grand scheme of things, still early days for it as an industry. We haven't yet learned the lessons that older industries have.