Maxperson
Morkus from Orkus
That sounds like a very 3e-based perspective, where the rules acted more like boundaries than they do in either 1e or 5e.
Obviously, and a DM has to make rulings whenever one comes up; and these rulings will of course vary from table to table (though I think we'll all agree that a 5-mile nuclear blast from a sword strike would be ruled against).
Even in 5e the rules provide boundaries. It just encourages DMs to stretch or break those boundaries as necessary. What I'm saying is that by the rules, if the rules of any edition don't say you can do something, you can't unless the DM says you can via a house rule or home brew. That holds true for 5e and 1e, it's just that those editions are friendlier to DM alteration or addition than say 3e or 4e.
But it really is a different perspective. In 1e (and, from what I can tell, in 5e) you may in theory try anything at a character level unless a rule specifically says you cannot. In 3e, however, it was more that you may not try something unless a rule specifies that you can (and if someone did try something outside the box the DM had to find a way to justify it within the rules).
Within reason. You cannot be a 1e Fighter level 1 and and say cast a fireball.
The same applies to what a DM may do. If I as a 1e (or someone as a 5e) DM decide that gods can grant xp, then gods can grant xp. If I decide they can't, they can't. There's nothing official anywhere to back it up either way. Rulings, not rules.
That really applies to every edition. I had no problem house ruling the heck out of 3e. Also 1e had the Deities and Demigods which included what the gods could do via the rules. So there was something official in that edition. 5e is really the only edition I know of where no such rules have yet been released.
OK. I'm used to 1e wishes that really could move mountains.
And difficult terrain, at that!
I still run wishes that way, though they tend to be limited by the power of the granter. A wish spell cast by a wizard isn't going to move mountains. He's not powerful enough. One granted by an Efreet, sure. One granted by a god could move a mountain range.