your phone chargers and powerbanks delivers less than 10W at most, because of the physical limitation of USB-A. The most you'll do is either you get a fizzled cable, overheated phone that will work fine once it cools down, or a powerbank gone kaput. Very low risk. Hence why you see TONS of chargers and powerbanks from brands you never heard of before capitalizing on the market hungry to barge phones. That is not the case for USB-C. Particular USB-PD. Your USB-PD capable charger may have printed specs stating it'll deliver only 30W (15V 2A for example), but if that charger isn't equipped with power controllers that regulates the power draw from your socket, an overcharging current runaway (more than 30W) can result in it drawing way more current than it should, USB-C cables are built to carry up to 100W(20V 5A). For faulty, out-of-specs chargers, they even store residual charge even when you pull them out of the power socket, because the capacitors fail to flush out the excess charge! Your charger burst into flames, your cable acts like a lit fuse, your device being charged explodes, and all this happens while you're in bed sleeping at night burning your house down.