Not sure why people are being so weird about answering your questions, but e.g. CloudFlare does DDoS protection which now basically everything you put on the internet needs some type of , and is far too complicated to do yourself, when you need it.
Thus CloudFlare (or AWS's equivalent) is pretty essential. I'm sure there are other reasons too.
The steam deck won't pull past 3A anyway (all usb C cables are rated for 3A), so unless you're using a USB-A to C cable, you should be getting full speed, unless the cable is damaged.