These apps, like all apps are prone to hacking, simply because they require users to provide access to their accounts.
Lending the 'keys' to your car to a thief is not something most would do.
ID theft is the greatest threat to the whole online computer industry, and may become the boom industry of the 2020's
Once on the net always on the net, and blockchains are no different, just more obviously so.
Recent hacking of big name twatter accounts may be a sign that we should all be more careful of what is or isn't online.
Time will tell
https://www.newsbtc.com/2018/11/17/twitter-on-the-defensive-blames-third-party-app-for-recent-scams/