The Pis, and especially the compute module forms, are used for more than just clasroom toys and low power geek desktops. The CMs are a long term support item that, in recent forms, are FCC certified with wireless. Because it's a "module," with onboard wireless/antenna/etc, you don't have to perform the (quite expensive) certification tests for a wide range of products that can then have a perfectly good little computer and wireless in them.

Unfortunately, when those aren't available, it's a problem for not just those who want Raspberry Pis, but for everyone who wants to buy or sell any of those products based around a Pi. You can't just trivially redesign to anything else, not that there's anything else available...

I'm trying to build some YARH handhelds for various projects, and outside the stock of Pis I have a few of, that's just going to end up on hold, because I can't get any of the boards I figured would regularly be in supply places.

It's another breakdown of JIT.