The real reason is that in contexts like the Settings app, where toggleable items are mixed with other items, checkboxes on the left would take too much space on mobile (especially on the early small-screen iPhones), because it would require the left margin to be increased for all items. Checkboxes on the right are awkward though, and thus were replaced by the toggle switches. The immediateness argument is just a convenient excuse. Immediately-effective checkboxes weren't uncommon on desktop before. In addition, there is "previous art" in the form of boolean-toggle menu items that are immediately effective and show a checkmark when active.
This assumption breaks if you use macOS. Windows uses (or used to use) Apply button in its settings. Macintosh OSes were reactive from the start. Which means that checkboxes have immediate-ness on Macs.
That was true in the 90’s when you’d post a whole page but these days the individual checkboxes are more likely to have event handlers that transmit state to the server immediately.
> That was true in the 90’s when you’d post a whole page
I'd say that to the extent that is true, it was equally true for radio buttons in the 90s.
These days I find myself scrolling around pages to look for submit/save/apply buttons to determine whether checkboxes and radio buttons are intended to have immediate effects or have to be submitted to be applied, because there really seems to be a lack of consensus on what these elements mean in those terms.
lstamour talked about two things, the proliferation of toggles, and the unclear toggle buttons.
ncruces replied clarifying the former, that the toggles proliferate because they convey immediateness. They didn't say anything about the "unclear toggle button" point.
Your comment, then, aimed to correct ncruces' comment, clarifying that lstamour was talking about unclear toggles, when ncruces was talking about the other point in lstamour's comment, and thus was already correct.
> Likewise I thought the article’s punchline was going to be the increasing use of on-off toggles instead of checkboxes.
That's the second paragraph. This would be those left/right toggles that became popularized with iOS on the original iPhone (since you could physically slide them with your finger). These also do have color insanity associated, though.
The third paragraph used "toggle" in a more general sense.
A checkbox is like filling a form, it requires submission for the action to take place.