I'm playing the tank in MMO's since Everquest back in '99....
If I get an invite to a group I don't care who has lead, most of the time I'm the one calling the shots anyway as most group rely on the tank doing exactly that. Only time I tend to sit back is when it's my first visit to the instance, but even then only if someone else has some experience with that instance. In an all first visit group I tend to take lead again...
... so no, inviting does not make you the leader ...