The crux of the problem is that US Crude (ie WTI on NYMEX) is physically delivered; while Brent (on ICE) is cash delivered. If I'm a say WTI ETF, then I won't have any account with any registered warehouse in or around Cushing to deliver the barrels to. So I can't take receipt and just sell those via the next month contract. So I have to sell this month's contract at ANY price, because I am not equipped to physically receive the physical delivery. Which is why WTI went negative; while Brent did not.
The problem here is the inability of financial "investors" (in WTI, but not Brent) to accept physical delivery. So they must sell, whatever the price. Even if they could "refuse delivery", then that's like saying they bought their oil, paid for it, and let the vendor keep it... the vendor being able to re-sell it at a positive price, that the buyer cannot. That's no solution.