Equipment enthusiasts will tell you that they leave their squat and bench suits in the corner of the gym when they aren't using them and never once have seen them perform a lift. Obviously pointing out the fact that it is still the person performing the lift.
The use of equipment in powerlifting has evolved from a injury prevention measure to a science of physics and leverage in order to drive totals through the roof. In the past, equipment consisted of a flimsy belt, worn "to keep my back safe", some weak ace wraps for the knees...and that's about it. The first advances came in increasing the durability of the belt...still no real harm done even if you consider the try power belts of today (lever or otherwise). Then knee wraps changed to the point people were wrapping tennis balls behind their knees for compression and drive (enter the need for newer and stronger fabrics). Today, knee wraps are wrapped tight enough to cause serious circulatory damage if left on too long. Lifters of old would wear singlets...put on with ease. Today, if you can get your squat or deadlift suit on with the help of only one person it's much too loose (in general). Single poly bench shirts were about all that was available 15 years ago, then 2 ply, denim, canvas. I know I'm leaving out some but I'm trying to hit the high points.
So what gets the biggest advantage? The bench, hands down. Take a look at raw bench totals compared to equipment (and I'm talking equal comparison lifter to lifter). We see, what...a 200-300lb jump. Squats are next probably adding at least 100-200lbs. Deadlifts are last IMO benefiting least from equipment. Why? Take a look at deadlift totals from 20-30 years ago. The best deadlifts of that age (Kuc, Inaba, Bridges, Pacifico...etc) could easily compete today, and your average lifters of those eras had the same deadlift totals today. Kuc pulled well over 800 with no belt (absolutely raw) in Hawaii at the World's. Think about putting Kuc in today's top equipment in all 3 lifts. He would probably refuse to wear it but I think you'd have the top total ever (pure speculation but an interesting thought). Now I know the best deadlifters of today outperform the best of that era, however it's not by the massive amounts as seen in the bench and the squat. I'm not saying equipment doesn't help the deadlift, personally I think I get about 50-60lbs from a good deadlift suit, but not near to that of the BP and SQ.
My point is where do we draw the line. When will it go too far. I'm sure I can bench 2000lbs with the new hydraulic assisted, counterbalanced, leafspring aided, electromagnetic trapper keeper 5000 bench shirt developed by Microsoft so Bill Gates is not only the richest person in the world but also has the best bench. I'm not taking anything away from the lifters of today. Nor am I forsaking the use of equipment. I personally use equipment as there is no way to be competitive if you don't. I also enter my fair share of raw meets. But are we going too far? When does it become more of how much your equipment can do rather that what you do. When will we see a guy with a 400lb raw bench throw up 800lbs? Are we there already?