It is not about not letting ppl shine it is about trivializing a challenge.
I guess there is a little bit of player perception here as well. But, certain class/race/background options really are hard counters to certain styles of challenges, while others are minor counters.
Hard to come by weapons, Monk isn’t hurt nearly as much as other classes, though being stuck with 1d4 for their damage dice the first few levels may also be kind of hurtful. Of course, alternatively, how many games are run where the players spend more than a session or two with zero weapon options? Once everyone has daggers or better the monk is doing fine, and spellcaster cantrips are generally even better than monk unarmed fighting unless there is also a restriction on their ability to cast.
But, run a “forest survival game” and a player brings a wood elf Outlander Ranger to the table, they’ve got a character who is supposed to thrive in the environment you’ve presented. This is exactly what they are built to handle, so doesn’t it feel a little bit wrong to ban them for that exact reason?
Where is the line between “I cannot use the challenges I planned on” and “I don’t want the players to have characters built to handle the challenges I planned on”
But imagine this philosophy "One world - everything goes" would be applied to a redo of darksun in the form of putting it into the anauroch desert. Every race class paladins whatever can be played. Otoh you now have cannibalistic halflings running through Waterdeep the Lords of the city will surely be tolerant in the name of no restriction.
I think í do not have to be clearer in what I mean, a setting is in part defined in how restrictive it might be on certain issues may that be no orcs , no water for DS, magic of the moons for krynn, paladins are like a shining lighthouse to domain lords in RL etc. And it is what gave these settings an unique feel to dm or play within, it was not your usual tool box or assumptions it was different and it was and still is great.
Let us instead of accelerating WOTCs "Lets take the best of old setting and put it into the realms (Ironically CoS with Bavoria is located in the FR when it still was on the prime!)" think about creative ways to make DS possible with the absolutely great 5E ruleset.
Lets think about whether Templar should be WL or Cleric or if a new subclass for barb is a good approach to Gladiator class, or how to implement halfgiants and thrikreen those issues still give me headaches, but instead the discussion here is how to shoehorn drow and dragonborn to a setting where they would fit like we say in Germany "like a fist to the eye"
But that isn’t…. ugh, so many different discussions to follow.
The line I brought up and Hussar was responding to is the restriction of things like Monks from Darksun “because they overcome many of the traditional challenges”. Not that they don’t fit in the setting, but that they are actually too good in the setting to be allowed.
That isn’t to say I want everything in Darksun. When I was introduced to the setting (through my first 4e game… I think my only major 4e game as a player as well) one of the big things that was driven home by my DM is that Athas is a land without Gods, the gods are dead, and therefore there are no clerics within Athas. And a restriction like “no clerics” not only makes the setting fairly unique in my eyes, but it does not harm the basic functions of the party. Bards and Druids and Rangers can still act as healing and buffing sources, so losing clerics isn’t going to massively change the balance of the game and it makes sense in the world. You could also so there are no fighters in Athas, but while the game balance isn’t affected the lore of that statement is… non-existent. Why would there be no fighters? In fact, could you ever come up with a setting where “there are no fighters” make sense?
And then we get to the difference between hard banning and soft banning. Personally, I’d place a soft ban on Druids in Darksun. Sure, they make sense as there are sections of the world where nature still fights back, but they should be incredibly rare. I’d encourage players to pick something else if they wouldn’t mind, because the feel of a desolate wasteland is much different when you have a person capable of drawing on a massive well of natural power.
If I sat at a table and someone said “No warforged in my Darksun game” I’d be perfectly fine with it, it makes sense as a restriction to generally have no warforged because they require a lot of support in world for them to be a major “race”. But, if I had a player who desperately wanted to play a warforged… I can find a way to get a sentient golem to fit into the setting without it causing everything to fall apart or to require them to come from another plane of existence (I HATE that explanation for why a character is in the world)
I guess, to summarize a lot of thoughts, there is a difference between omitting an option and banning an option. I have never had a cleric played in any of my games, no player ever wants to play a cleric in my world, I’ve also never had a dwarven player in my game.
So, if the rules don’t explicitly ban an option, but instead leave that consideration to the DM, then I think I’d be cool with it. But, I also might appreciate for an official setting, if there was a section (perhaps towards the back) where they said “IF you really want to add this race or class to this setting, here is where it will cause the least amount of disruption” because that will help DMs who are new to the setting. Spell it out as optional, and then let people do what they want with it.