Yeah, that's exactly what the slingshot method is. The problem with using the slide stop as a slide release is that it's easy to miss it under stress, if your hands are sweaty or greasy, or if you're wearing gloves. Also, every gun is a little bit different so using the slide stop as a release requires a slightly different technique with every gun.
An acquaintance, a pro-shooter and high-level IPSC competitor, has been working as a trainer with Special Ops troops at Ft. Bragg for a number of years. They do a good bit of force-on-force drills using simunition, with both pistols and long guns.
He noted, several years ago, that the U.S. Military had STOPPED teaching the sling-shot method. Far too many stories were coming back from combat zones about soldiers having to rack the slide a second time, one round down, when reloads were performed under fire. It appears that fine motor skills are ALSO required when doing a sling-shot release -- especially when wearing gloves in harsh environments.
The DOD now teaches shooters -- at least in the special ops classes -- to use the slide release. With some guns, using the release can require changing your grip, but using the offhand, using several fingers rather (in a sort of claw) rather than just one finger, makes missing that little lever much less likely, and the same technique works with most weapons. I started doing that some years ago, when I was shooting IDPA regularly, and found that I was just as quick and reliable as before, and didn't have to change my grip. (I've got a number of handguns and only two really allow me to reach the slide release/stop lever without changing my grip.)
One point seldom addressed is that the slingshot method forces you to move the gun much farther off target than when you use the slide release. In competition, this is important -- and a "time" issue. In a real life confrontation, it might also matter a lot.
That said, knowing HOW to do a slingshot release is a normal part of the clearance drill, so it is something you must practice.