That's what I think too. You get the (extremely old reference here, but you get my drift) Fred Dursts of the world to buy a rainbow of Yankee hats, and maybe a small percentage of them dig deeper to find out what the interlocking N and Y means. Either way, MLB makes money and maybe gets some fans from a pool that they wouldn't normally have.It’s not an either / or thing. Those things can happen simultaneously.
But while you're marketing to non-fans, hoping that they become fans; you can also build the game up through more traditional means like you mentioned: youth initiatives and minor leagues*. You cast that net as wide as you possibly can because in the short-term you'll make money and maybe in the long-term, you can make fans who will spend even more money.
* And this has been said a million times, but MLB streamlining minor league baseball was about the dumbest long-term move any sport has made in some time. Does it save the owners money today? Yes. Of course it does. They don't have to pay ~140 players a wage (which was peanuts) when they can pay ~100 players a wage (which is honey roasted peanuts). They also don't have to have a draft that goes 30 rounds, saving them even more pocket change. But the relationship that a minor league team has with its home town and surrounding area is immeasurable. I've seen it myself this summer now that there's no Lowell Spinners. My kids aren't die-hard baseball fans but they liked going to Lowell and running around the park. We would go with another family and it was a good, cheap time. And there was a Sox connection (I saw Benintendi hit an absolute bomb there one day) that was great. But it's gone.
And it's not just gone from Lowell, but dozens of cities and towns like Lowell. A lot of those towns aren't lucky enough to have a major league team 30 miles away either. This was about as close as they were going to get. Once that's gone, people turn their attention elsewhere. It's really difficult to get that attention to return.
Of all the things that Rob Manfred has done to try and ruin this game, this might be the worst thing.