The fact that I'm not competitive is proof in itself. I've faced casuals using it, and it fails to do anything besides waste 1 PP of an opponent's move.
More in-depth, I faced my cousin using it. My cousin doesn't EV train, disregards natures, stat-boosting moves, Egg moves, and IVs, and she doesn't even know most of what type is good against what type. My Jolly Ariados, EV'd in Speed, with Sticky Web, Toxic Spikes, and priority Sucker Punch, held nothing against her. Every time I sent it out first, it died first. And no, it's not just luck, I asked her to switch around her Pokemon's order so that a different one hit Ariados every time. OHKO'd. Every. Single. Time. If I can't even get out a Sticky Web, what good is the spider? And Focus Sash might stall for it, but one Sticky Web isn't worth an entirely team slot. Alright maybe it is with Sucker Punch's priority afterwards but I still don't think it's good at all.