From my experience on another V Bulletin forum it is generally frowned upon. There are plenty of hacks via Tapatalk that can cause headaches for forum admins.
There are even forums out there discussing "how to hack" with Tapatalk.
Not sure why its even necessary if you are browsing via a smartphone.
Oh I know and I have friends that use it on different forums and they rave about it. You would have to have Fred Zed decide on it.
Another forum I participate on the owner is quite knowledgable about these issues and the hacking does lend itself to find a way into different layers of the VBulletin 4.0. Particularly, via the photographs is where hackers have found the vulnerabilities.