Li Shenron
Legend
We've seen how this works out for the last 30+ years though, and what actually happens, is two things:
1) Gods who have potentially onerous restrictions on behaviour for adventurers just do not get chosen by players, or on the rare occasions that they do, last like two adventures before being retired or whatever. No, that one time someone played an SP of Illmater or whatever, and against all odds, it worked, doesn't mean the general trend isn't a big issue.
2) Loads of domains are powerful, and any gods with "adventurer-friendly" tenets will get played, and the players won't even have to alter their behaviour, because, in old V:tM terms, they picked "The Path of What I Was Going To Do Anyway". So you effectively just limit the pool of domains to "whatever domains are possessed by adventuring-friendly gods".
And this is essentially an RP restriction on a single class, which is gains nothing for it. Which isn't great.
What, seriously? There is basically a deity for everything in the history of D&D. Sure if you play a specific setting you might have to stick to a limited pantheon. But if you play for example Forgotten Realms you can be whatever cleric you want to be... I mean you even can be a "priest of slimes and other assorted filth" (Ghaunadaur) if you want. The RP restriction kicks in only after you've chosen your religion, not before.
But anyway, if someone asks for suggestions, I try to give suggestions. It's just an idea and I don't necessarily play this way myself. Actually, I do roleplay my Clerics PCs this way as a player, but I've never taken away someone's spells as a DM because of how they were roleplaying. The restrictions are as onerous as the DM wants them to be, there are people who literally play LG Paladins as psychopaths and don't care what others think.
I merely proposed an idea for "differentiating arcane and divine magic" as per the title, it obviously assumes someone's players are OK with it, or they'll look at another idea. Otherwise, why not raising the objection that for the last 30+ years most players actually didn't really care much about the difference between divine and arcane in the first place?