Do people just not care how loud they are?

I got this game yesterday and the entire tutorial drilled into me that being stealthy is the way to go, don't be noticed.

I load into an actual game and I can hear people charging around and jumping up and down. It's so easy to know when people are around, meanwhile I got the drop on a pair of people and got 2 kills in my very first match.

This isn't a level thing, I also saw rank 100s in the spectator menu that don't seem to realize you can release shift.

I still haven't successfully extracted from a mission because I end up taking a 12 gauge to the chest in CQC, but still. Am I being overly cautious?