I tbh run alternate java's in a windows VM. Whatever apple ships with and updates is what I run on it. Not a big java fan, above reason of version conflicts one of them, so I avoid this version games on host mac os if I can. I find it gives me a nice cutoff. Is what is needing something different worth firing up the VM? Sometimes the answer is no lol.
reason for needing SDK over JRE is most likely Google pulling on libraries specific to JDK. Google not really to blame there fully. Its also java being java and pulling this crap. Most languages give you all in one on the base install. Just add additional stuff as needed which are usually just specialized coding. Like say Bio-python, adds support for Biology work via premade functions and such. Non biology users would not need this...so its not pulled down by default. Only other language offhand I know that has a developer core install is R. And it has that to build packages by and large. Not making your own packages, you won't need to pull this down most likely.