I don't associate these phishing pop-up survey ad pages with my iPhone/iOS/Safari exclusively. Happened more frequently with my Android phone a couple years ago when I was running the Chrome browser. I expect it to happen when I visit certain websites like the Houston Chronicles website, chron.com. However all that, has been much less of problem after switching to iOS/Safari. Was kinda surprised when it happened upon pulling up the first website of the day... which is nearly always DU, and today was no exception.
Today's round of internet buggery was squashed when I closed the last ten of my open tabs. Included such things as DU, Wikipedia, and ticket purchasing pages for the Jeff Beck tour dates in San Antonio and Austin. Didn't have to clear my entire history, or toggle the recommended settings... Which I believe I already did a few months ago. I use duckduckgo as my search engine, and while I'd like to believe that's one of the reasons these intrusive Congratulations, user! pop-ups have decreased, I'm not sure at all.
Btw, I'd be leery of any website offering a way to clean or protect your computer or phone from these pop-up pages. I generally avoid any service that doesn't have real money/investment/history behind their name. I would love, love, love... I mean, love, for a major tech publication like Arstechnica, etc to call out exactly what's happening with this Congratulations web spam crappola.