because if there is a oil blockade banning the sells of all oil(yet supply continues to pile up). then even the futures market will see this and be on a downside not an upside. (those with active contract will be trying to sell them at a loss becasue the contracts wont fulfil so they will want any dumb chump to buy their empty bag of contracts off them)
and when the blockade finally gets removed for actual oil. there will be alot of people ready to sell and everyone clamouring over each other to sell before the next person, thus causing a dump
same goes for real estate. those holding mortgage derivatives know that they are holding a losing contract. and so while tenants are foreclosed on because they stopped paying mortgages, the investors will want their money out but unable to sell the house so they just foreclose on tenants and hoard unsellable real estate, leaving homes in disrepair.
then when real estate market opens again everyone will be clamouring to auction off dilapidated/unkept houses for $1 just to get rid of their contract but knowing the tenant still owes them full amount of debt tenant didnt pay.. because well thats what happened in 2008 in one way or another
when there is a large stockpile of assets that cant sell.. the prices dont go up.. they go down
It seems to me that you have little experience in the market. Let's take the year 2020, when oil prices fell by ~90% (WTI ~$2, Brent ~$5). If your claim is correct that the price is determined by the balance of supply and demand, does it mean that humanity reduced its oil consumption by 90% in 2020? Roughly speaking, by 10 times? Of course not, the actual reduction in consumption may have been around 10-20%, but not 90%, indicating that the price of oil was determined by the derivatives market. Similarly, your second example about the 2008 crisis is also entirely flawed. Do you believe that in 2008, people started buying 3 times less real estate or constructing 3 times fewer properties? Even in the case of real estate, the price bubble was inflated in the derivatives market, not in the real market.