It sure must be a pain for traders to experience such issues but we all know how high the trading volume on Binance is.
At times of FUD and FOMO the traffic on the site gets bigger and bigger which makes the site to go under a maintenance.
It is one of the disadvantages of a centralized exchange. It's better to have your coins store on multiple exchanges to tackle such an issue.
You would at least be able to trade a portion of your portfolio this way.
That's why you need to think fast before that happened because when the downtime is fixed, the price of BTC might sink to the bottom, and you might lose your chance to sell your BTC at the high price. Yeah! you're right we choose those popular decentralized exchange for their convenience and safety but if ever panic trading has come, then we need to make some best alternative and the best alternative I can suggest is moving your assets to USDT because that's the only way to preserve the current price before you get caught with the downtime.
But if the site is totally down (meaning we can't even login) then how would the user exchange his coins for USDT.