In exploring ideas that I hit a wall on I routinely will seek input from the Stackexchange communities, occasionally these ideas result in that it's really just not possible what I want to do.
I feel it's somewhat misleading for my questions to show that they have answers but none were accepted because the question has no solution, or I feel that I should arbitrary mark someones answer as accepted to acknowledge I valued their input.
Neither of these seem to be the optimal end result of a question that is determined to not be able to be solved.
I propose that questions should have some kind of not viable, not feasible type conclusion. If this was to be added, it probably should require a medium level of reputation to accept that as the solution to prevent inexperienced stackexchange members from picking it when they just get answers they don't like (especially on show me the c0d3s posts).