See, the thing is, plan errors and gross execution errors can be detected with reference to the plan or design itself. Internal consistency checking of the geometry — a math problem — can be done with just the design. Gross errors like off-by-1-hole can be detected by checking the evolving physical artifact against the design through discrete validation processes, a kind of syntax/grammar checking comprising, in the case of Meccano, things like counting holes. The problem is within the realm of what computer scientists call formal verification. Detecting errors in plans or in idealized execution states is something like proving theorems.
But tolerance stacking is a problem that is “outside” the scope of the abstract model being instantiated. It is about unmodeled realities seeping into platonic realms that are not aware of its existence. A version of illegibility assaulting high-modernist thought.