Sacrosanct
Legend
Except when your party needs to make an arcana check and someone is forced to be a wizard. Or the only one who can heal is a cleric and someone is forced to play one.
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I don't think anyone is forced to be anything. Even in the edition with the biggest niche protection, 1e, you didn't need to do that. There were other options. No one can make an arcana check? That's what towns were for. No healing magic? That's what healing potions are for.
Now that I think about it, that's another big difference between TSR D&D and WotC D&D. Back then, parties had a base of operations where they went to several times during the adventure. A place to heal, to research, etc. Nowadays, it seems as if once the adventure starts, the party stays on path until it ends, thus sort of making it mandatory that you have classes that can do all of those things that were done back at the base.