While, personally I think adding “much” to that explanation is hyperbole, I can understand the encouragement.
You can definitely tank in Arms spec. Here’s a Classic Warrior Tanking Guide I put together that may be of some interest to you, as it includes some macros, etc. that might be helpful if you’re unfamiliar with them otherwise.
One of the benefits, I suppose of being able to tank is that you may be able to find dungeon groups slightly faster than as a DPS (Note: I say slightly faster, as that is my opinion, and experience so far. If you are actively putting groups together yourself, and able to make friends along the way, there doesn’t appear to be a lot of difference in time to assemble a group, regardless of your role. This may be different if you are passively leveling and asking to join groups, as you find them.)
For the most part, me too 