Because in many cases, only one person rolls some checks.
If that is a common occurrence, the DM needs to read the DMG and think through scenarios more in the context of having multiple simultaneous moving parts to a challenge. (As usual, this is a DM guidance issue, not a RAW issue)
There are some checks multiple people get to roll. Or group check where everyone rolls.
But some of the checks there are only one roll: To inflict penalty, loss, or bars upon failure.
Right. Sometimes a situation calls for a single roll, sometimes it calls for a whole scene. Which makes the fighter subclasses giving extra skills not an OOC feature…how?
One person gets to navigate.
One person gets to pickpocket the guard.
One person gets to convince the official.
Others can help. But working together does not use proficiency unless it requires it which pretty much is only for picking locks and disabling traps in core.
That’s the only explicit example. The language does not imply that other checks don’t fit the bill.
Beyond that, so what? If the rogue is already navigating, they aren’t pickpocketing the guard. If the Bard is seducing I mean convincing the official, they aren’t examining the portal runes.
Multiple things to deal with, one scene.
In addition, multiple persuasive characters can be doing different things in a conversation, or an insightful character can be reading someone while the persuasive PC chats them up, etc.
So only one person between the Fighter Rogue Wizard and Cleric gets to track. On failure you lose the tracks. So the fighter and cleric both having Survival is redundant. Because you only need one person with Survival.
False. The above is only true if the game isn’t giving the characters several thingns that need to get done in the same span of time, and the players are always hard-optimizing every aspect of the game.