How you will solder a thousand ball BGA part as in the video with a soldering iron?
Almost all surface mount is designed for hot air. You can touch up an MLCC with an iron but you are very likely to crack it with uneven heat.
Yes, but certainly not every repair requires replacement of a bga part. The most common are screen, buttons, usb connector, aside from the port, all other are purely mechanical.
Apple doesn't really use through hole parts - the connectors are SMT. I can't see any high volume repair shop using a soldering iron on SMT parts when hot air is so much easier and faster. A hobbyist might, but only because they don't have the hot air rework tools.