I don't know anyone who says they rely upon double-action in lieu of safe handling and good trigger discipline. What we're saying is anything you can add that (1) doesn't slow you down if you need the weapon yet (2) enhances safety even a little so as to (3) mitigate the all-too-common human propensity to err is a good thing.Relying strictly on the DA to "cover your arse" is as as foolish as pointing a loaded gun at your foot and and touching the trigger.
Since this post caused a recent new P99 buyer to misunderstand the P99 manual of arms, I'm posting a correction:AS mode, since 1999. As Gmountain pointed out, there's really no other reason for AS mode to exist and as UE mentioned, and I can confirm, until 2008, IIRC, the Owner's Manual did not recommend carrying decocked. Even my 2009 built P99c came with the older version of the manual. I don't remember exactly when they changed it, though the revision date of the manual should be on the back cover, but like most manufacturers, they continued issuing the old manual until they ran out, which is how my 2009 got the older manual.
Since the act of holstering is clearly not the intention to fire at once, decocking before holstering is the only course offered by this passage."If the weapon is not to be fired at once, decock the pistol by pressing the decock key."