First, not everyone cares that much about gripping a football or competing in powerlifting. And even powerlifters use straps at certain times for overload work. Second, the use of straps doesn't have to be a crutch used for every set of every exercise. Your grip strength will be fine and way above average even if you use straps for a set or two.

For building muscle, straps allow you to:

1. Get more reps with the same weight. You can do 6 reps of 410 on the deadlift without straps? Good, now get some straps and you'll probably add a couple more reps. What's more important for overall strength and growth? Those extra reps are, silly.
2. Use more weight for the same number of reps. Same example: you can deadlift 410 for 6 reps. Add straps and maybe you can do 6 reps of 420. That's huge. And you're not a competitive powerlifter, so who gives a shit if you used straps?
3. Increase training volume by being able to knock out another complete set when your grip gives out before your muscles do on pulling movements. Do a few sets of pull-ups, pulldowns, or RDLs without straps, then do a bonus set with straps.
4. Increase training volume on certain lifts like the deadlift. As Christian Thibaudeau has written, using straps when deadlifting decreases the neural demand and allows you to do more volume or ramp up frequency. Basically, straps give your fried CNS a break because grip-centric exercises are harder on the central nervous system.

All four of those contribute to that thing most people are after anyway: muscle growth. Seriously, are you training for bigger muscles or to enter one of those fat-guy grip strength competitions?

Just about every pro bodybuilder uses straps. I've trained in Vegas around the time of the Olympia and at Gold's Gym Venice. The gyms were brimming with every top bodybuilder, pro wrestler, and figure competitor you could name.

All of them used straps. And all of them have better physique development than you. Their forearms were huge, too. And none of them gave a rat's ass that some little functional training dude said that straps were bad.

Get the shorter ones. You don't need to wrap the bar or handle five times, and short straps are faster and easier to get on and off. Leather adheres better to the bar and lasts longer. It also pisses off vegans. I like the 17.5-inch double-stitched straps made by Rogue.