A strike carrying a large amount of positioning shows up on a dealer map as a concentration, and it frequently behaves like a level: price approaches, slows, turns. People call it support, which imports a set of assumptions that do not apply.
Where the resistance comes from
Traditional support is discretionary. Buyers believe the asset is worth the price and place orders there. They can change their minds, but they chose the level.
A wall is mechanical. Dealers hedging a large position at a strike trade against moves toward it because their hedge requires it, not because they have a view. Nobody at the level wants the asset; they are managing exposure.
Why this predicts failure differently
Support fails when sentiment changes — buyers stop believing. A wall fails when the positioning behind it stops requiring the hedge, which happens for reasons unrelated to sentiment.
Expiry is the big one. A wall built on positioning that expires this afternoon is gone this afternoon, regardless of what price is doing. Traders who treated it as support are left with a level that evaporated on the calendar.
A wall can also drain during the session as positions are closed. The map showing it at ten may not show it at two, and price will behave accordingly.
How to actually use it
Check the expiry the positioning belongs to. A wall on a distant expiry is durable; one on today is a same-day phenomenon.
Watch whether it is building or draining. A concentration growing through the session is being reinforced. One shrinking is being dismantled, and the level will stop working before it disappears entirely.
And size positions on the assumption that it can fail without warning, because unlike support, it can fail for reasons that have nothing to do with the market.