Well at least it shows that they have a working platform. There's now a trend of developing a app before launching the ICO. Web wallets and exchanges does it with priority.
If the platform really works than they'd gain some credibility but if it's just a web app, there's nothing they'll gain.
It doesn't prove anything. They can make a simple app by spending a small amount of money and some of the early crypto based are as useless as they were before.