only casuals use the joystick to jump. By disabling joystick jumping, makes it a lot easier to do up tilts (lightly hold up and press a)

also have more control over your jumping/short hopping by using the buttons I find

i also find it easier easier to do down/side "A" while jumping

Well guess that makes sense I really barely played any other smashes besides the 64 version but I'll hafta try it out

Depends what you're doing. When I short hop or wavedash (in melee/pm) or w/e, I'll use buttons to jump. For jump cancelled actions out of shield (like upsmash or something) or for full hops, I usually use tap jump. You'll see tap jump used at all levels of play, but that doesn't mean for some actions they aren't using button jumps as well.