There's less data tying you to your identity with the web apps, and you can use an adblocker to reduce your profile even further. The location data is troubling but I've seen at least one of those randomize the pin slightly each time it updates your location, though in a circle radius so I guess you could triangulate it by staring at the pin a bunch.
I am not entirely sure I by there being less data. I don't allow Grindr or Scruff access to anything on my phone. Even for photos I use the iOS feature to limit what photos they can see. The only real difference between the... accepted profile structure. Grindr and Scruff tend to be face...ish pictures vs Sniffles that is... not.
Facebook and Google have become very good at tracking you across the web. Sniffles has ads (admittedly all of them are to sign up for premium but I don't know how those ads are served... I have not looked).
So add in google fonts or some other tracking mechanism and suddenly you have a ton of data to tie someone too a website that is meant to be anon. (more or less, I know its not quite that simple but I don't think being on the web makes it necessarily any better)
