So, there's a few problems with the approach of giving such entities stat blocks. "If it has hit points, we can kill it" is a mindset a lot of players have. There is no reason to have a 60th level opponent in the game. None. Zero. Zilch. You could just say "Odin wins" and that's that.I find it funny how in 3e, the official Odin had an ECL of 60 without counting Divine Abilities.
It makes it really jarring when people actually as though you become invincible at Level 15. That just tells me that the DMs aren’t trying enough imo.
By defining his powers, you define his limitations. Because of how the magic system is designed, each distinct spell is a solution to a problem. In 3e, players routinely found obscure spells that let them find answers to any issue. I'm sure someone could figure out how to kill Odin without DM fiat being used.
I remember a discussion about how a couple of 10th level characters could take out the Tarrasque with relative ease, for example.
The issue most DM's have, I suspect, is they want to "fairly" challenge the players without resorting to fiat like no magic zones or abilities that just say "no you can't do X", or having to ban half the spells above 6th level. It's not that they can't do this, because they certainly can, but that they feel it's somehow unfair to have to negate the player's agency and abilities that the game gives them, in order to make the game work.
The game should work as written, and if it doesn't, that's a problem. It doesn't matter if rule zero exists and you can fix it- you shouldn't have to.