Let me ask you this question. Do you know who the wealthiest owner in baseball is? (Hint, he's not the owner of a team in the AL East, he's the owner a perennial good, but not great team). And as of a year ago, only one of the top five wealthiest owners in baseball was from one of the team's that call themselves a big budget team.
That being said, I think I'd prefer a tougher luxury tax before I'd prefer a salary cap, at least on my initial thinking of the matter. I haven't really given it much deep thought lately.
And yes, much like life, baseball isn't fair. But still, it's an input-output scenario. If you put good people in positions for success, manage well, and don't take shortcuts, your chances of success will be much higher for the long term, but not guaranteed.