Which goes back to the original point of this thread (at last!).
Some DMs forbid some multiclass combinations (read: paladin/warlock) for what they claim are 'fluff reasons'.
The reason that this approach is absurd is because they are pre-banning PCs before they even know what this particular PC's fluff actually is!
They are assuming that the as-yet unknown fluff will include two gods/patrons/powers that will not allow their 'servant' to serve two masters! Sure, that would be a valid reason to ban a PC....IF that was the situation!
But it might not be that situation! The 'green knight' Pal/War (ancients paladin/fey patron) is just one example from the PHB which doesn't need a 'you MUST be a powergamer' explanation, and there is no reason to automatically assume that god/patron could not work together, or even that god and patron cannot be one and the same being.
My first Pal/War PC's fluff was that The Fiend was pretending to be Odin, in order to corrupt the young paladin. So, Pal 2 to start, then MC to fiendish warlock 3, becoming a chainlock to an imp which ALWAYS kept it's raven form in front of my PC, pretending to be Odin's raven Huginn! But, although my PC believes that his abilities (both from the paladin class AND the warlock class, although 'class' is a purely metagame construct and has no place in the in-game reality of my PC who is just a person with a list of special abilities granted by 'Odin') come from Odin, ALL his special abilities in fact come from The Fiend.
With that fluff, "the paladin/warlock multiclass is banned because the god would not allow their servant to serve two masters" simply does not apply.
Pre-banning something for 'fluff reasons' makes no sense because you don't know what the fluff is yet. The player creates the fluff for their own PC, not the DM.
pretty much sums up several of my posts on the subject but does leave out one point.
it only makes sense to pre-ban combos for fluff if the setting/world forbids such fluff.
As i have said in my other post, it seems incredibly limiting to one's divinities to say they are not capable ever of using intermidiary lesser beings for a variety of purposes - including serving as go-between and as patrons. it seems extremely limiting to decide your campaign "gods" of magic cannot actually use an intermediary being to provide more access to magical abilities to their followers most devout to further serve their cause - as cleric-warlocks.
A Gm could rule in his setting that all his divinities are so limited they cannot or will not do this even tho it helps them - even though the divinity itself is using the intermediary to do the light work etc - not a case of some other player getting in the game.
In which case, well, that would likely need to show in a lot of other ways thu the game like very very strict dogma to be followed and clearly established conflicts/rivalries/competitions between the gods being a major thing in the world - at least as strong as the influences found in the greek myth. In the greek lore, and myth the gods were active, constant players in affairs - but even they were willing to send lesser beings and intermediaries to work with and act as go betweens. So whatever this world is where the gods wont or cant - wow, might be even worse.
