I haven't personally downvoted you, but I would assume it's for one of two reasons:
1) The distinction if browsers ship their own engine or just embed system provided WebKit is ultimately irrelevant to the question at hand. I can go on the App Store and download "Chrome" or "Firefox" and use those applications to access websites.
2) Browsers do have age ratings on the App Store. It's 17+.
EDIT: Getting downvoted. Is this incorrect?