> they don't want to cannibalize App Store revenue by letting people type in code to solve their problems.
This seems implausible as a reason for keeping dev tools off iDevices, because 1) what percentage of their users would do that in the first place, beyond using spreadsheets, which are already available? Would it even be 1%? 0.1%?, and 2) they've made moves to add features like Shortcuts that enable that sort of thing, but which productivity-nerd non-programmer project managers and such are able and willing (and eager) to use, unlike dev tools—and those aren't just toys, they can absolutely replace certain kinds of what might could have been paid apps, before.
I think it's more likely that it's hard to add them without opening up security holes and making it easy to bypass the App Store and/or offer a 3rd party store, without making the tools so crippled that they're insufficient for actually developing & deploying serious software for oneself (in fact they've already released something so-crippled, in Playgrounds), coupled with their expecting extra sales of iDevices from adding dev tools to be tiny (so, not worth the cost & risk).