Over thinking it is usually a good thing and yes the course has changed a lot over the years. When I started most divers didn’t have depth gauges or SPG’s so the answer was; not faster than your bubbles!
They are teaching you to trust your gauges like a pilot on IFR but I have had both die on the same dive so then you need to pick a point of reference, the anchor rode or deploy a SMB and measure your rate of accent, do your stops.
PADI ’s lawyers don’t want you suing them when you get bent on their tables, they would rather you use someone else’s computer.
BTW, if you wear your computer on your left arm then when you raise your arm to vent your BC the accent alarm will go off :(