This puzzled me, too. Candles can get pretty expensive, when you can buy such good battery LED lanterns for cheap now.
Candles also produce heat and are pleasant for many, they can be used under sinks, for backups in case of running out of batteries and they don’t have a shelf life.
I have my blackout lighting needs met but also keep candles.
Some people may even be using this as an excuse to stock up or splurge on candles that they wanted to buy anyway.
You have to charge the LED lanterns somehow. Plus they don't do much good when you are freezing to death. At least you can huddle around a burning candle.