Based on these responses I fear my point (and the connection to the topic of this thread) may have been lost in the exchange of posts. To summarize, here's a fleshed out example and an explanation of my point:
The PCs have succeeded at their goal of fomenting large-scale civil unrest, but were identified while doing so. They know the king's spies will be looking for them, so they decide to lay low in a safe house. They receive a desperate request to meet from an ally of theirs, so the PCs decide to take the risk of sending the sneakiest among them to meet the contact. After considering various routes, the chosen PC decides to make her way over a bridge that is packed with rioters. She suspects (but does not know for certain) that the bridge will be watched. She declares her goal is to make it across the bridge unspotted and her approach is to blend in with the crowd, not hurrying, gradually moving across the bridge in time with the natural fluctuations in the crowd.
So far, so good? I think everyone would agree that there is a meaningful consequence for failure to get across the bridge unseen. And if (and only if) someone is watching, there is also an uncertain outcome. There are two competing approaches being discussed:
(1) Narrate the PC's journey over the bridge, and only call for a stealth check if/when she approaches within sight of a potential observer. If she makes the check, narrate the success. If she fails and there is an immediately-visible result from the failure, narate the failure. If she fails and the result from the failure is not immediately visible (but may be crucially important later), narrate the same result as the success. Whatever the check result, the cost of this approach is that player now knows whether or not the bridge is watched.
(2) Call for stealth check first, regardless of whether anyone is watching. Narrate the character's journey across the bridge exactly the same way as in #1. The cost of this approach is that the player knows the check result, and thus knows that it was likely they were observed if an observer was present, even if there was no immediately-visible result.
Both approaches are perfectly consistent with requiring the players to state their goal and approach rather than simply declaring a type of check. Both approaches are also perfectly consistent with only rolling when there is a meaningful consequence for failing to achieve the goal. So both approaches are within the bounds of the assumption of the thread. Both approaches also involve giving the player information the character does not have (i.e. metagame information). (As
@Charlaquin points out, these are slightly different varieties of metagame information.) My point is that even within the playstlye assumptions of this thread, different posters will have different ideas about which option is preferable.