I wrote extensively for a number of sites and magazines about NeXT technologies in the mid to late 1990s, I can give you chapter and verse on the history.

The number of developers increased in absolute terms just as they did when the iPhone came out, but the ratio of developers to regular users didn't, because the technologies mainstreamed and the sales to regular users were very high.

Back in the pre-acquisition NeXT days, the ratio of developers to users was incredibly high because overall sales weren't that great.

Thanks. I should have included that part; after The Return, the number of programmers on the Mac do indeed become visible again.