With rabbits, a common myth is that if you touch a baby rabbit the mother will no longer care for it. 9 times out of 10, the mother will return to care for the babies after they have been handled.
QNX is not a Linux distribution, normal or otherwise. QNX is POSIX compliant. That means that much of the programming interface and many of the utilities are the same. The underlying OS is very different in structure. There is little compatibility for drivers. With Linux the operating system functions as a very large monolithic piece of code.
There is a lot of misconceptions about the purpose of the UNIX/Linux Oracle user and the need for the dba UNIX group. At Oracle install time, the dba group and the oracle user are created. This user is created as part of the the dba group and the oracle user.