Not necessary. I put in an air gap on my dishwasher when I first got my house and read that they were supposed to be better than a high loop. Removed it when I replaced my laminate countertops with quartz and haven't had a problem since then. When I re-ran the drain line after the countertop installation, I noticed the dishwasher had a high loop built into it, so you may not even have to do one yourself.

Any backflow is going to be minimal and will only happen normally when you're putting gallons of water down the drain at once, then will be pushed out the next time you run the dishwasher. As long as you're not putting big chunks of food down the drain, which you shouldn't be doing anyway, you'll be fine.