Do not treat the lid as general load-bearing shelving unless the manufacturer explicitly permits the intended use. Weight can hinder opening, damage fittings or conceal poor closure.
What the observation tells you
Removing a heavy stack every time also encourages prolonged opening and awkward lifting. Objects can slide off as the lid moves. A lid that closes under external weight may still have an underlying seal or hinge problem.
A useful next step
Use proper storage shelves and keep access clear. If the lid no longer stays or closes as intended when unloaded, arrange assessment. Do not rely on stored items to hold it shut.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.