Here it is. https://www.bloomberg.com/news/articles/2015-11-03/that-time-i-tried-to-buy-some-crude-oil
From a regulator and exchange perspective it is the responsibility of brokers to prevent physical deliveries for retail clients. IB predates the last trading dates of CL contracts each expiry. I heard of several cases where retail clients were not made aware of that by their brokers and ultimately the brokers had to sort out the mess (breaking contract, fees, conversion to cash settlement...). Yes, ultimately it would be the responsibility of each trader but re retail generally the broker is on the hook for such mishaps.
If your broker is IB you would have received a couple of warning email messages during the last few days before expiry (or First Notice, if that date is relevant). If you did not take action, then they would have closed your position. For each contract you can find here which cut-off dates they use: https://www.interactivebrokers.com/en/index.php?f=1567&p=physical
Today is the last day of trading. After that, get ready to accept or deliver 1,000 barrels of Crude. We do not allow our customers to enter the delivery period.
I'm not familiar with that rule but as a practical issue, if you do not claim to be a hedger when you open your account, the FCM would likely liquidate you or look for a buy/sell of the contract in the cash market. We use Wedbush Futures and they can facilitate delivery for their clients and have many that do.
Back in the 1980's, was not very computerized like today, brokers did not keep manual eyes on their clients. I kept a corn contract too long and broker called and said I be needing to pick up 5,000 bushels of corn, WTF? That little mistake cost me $4500 of getting someone else to buy it, so new buyer pretty much bought it for 20% than normal. I would have not minded actually of receiving, but it is not like UPS coming to front door, it is you going to Chicago, locating it, having enough semi's to haul it away, then storage and then selling it. No, it was another dumb mistake and pile is quite large of all the dumb mistakes I have done in this business, but stay with anything long enough, you really figure how the game is played.
As Robert brilliantly explained a FCM will typically close out a spec futures contract before first notice day on a physically settled contract - their unilateral right to do so is explained in your clearing agreement. And they will charge a substantial fee for the inconvenience. There is an OTC Exchange for Physical (EFP) swap that trades after first notice day that some very large proprietary Specs and Commercials use after first notice day to cancel out delivery obligations. Moral of the story: know your contract specifications. Another reason this is important for spec traders is because for physically delivered contracts the trading can get crazy and downright bizarre before first notice day as those holding open positions either flatten up or roll their positions using the the prompt-to-second month calendar spread.