Agree with what? That Apple can't control the vastness of the Internet?
No, her iPhone isn't useless, and yes, it's just as safe as any other Internet device. And with iOS, the most secure OS currently known to exist, her iPhone is safer than any other device you can currently buy.
It's been said more than once, and I said it in my post right before yours. Get an ad blocker. There are a number of free ones that work very well. All you have to do is open the App Store on your iPhone and get one.
User Tezcatlo has a lot of good points, though one isn't possible.
Last, ALWAYS use https and not http when going to a website as it is more secure.
Can't be done. The site you're going to has to setup secure access on their end before you can use an https connection. Most don't. Simply adding an "s" to the URL isn't going to automatically result in a secure connection. Actually, if they don't have secure access setup, you won't get a connection at all.