This is not a matter of a cultural shift of today vs yesterday.
MLB is the only sport that openly and proudly celebrates breaking the color barrier, which they also openly and proudly enforced for decades. The NBA and the NFL allowed black athletes at some point, but just did it and moved on. That's not about yesterday vs today. Those are all events that happened in the same timeframe.
If I asked you who was the first black player in the NFL, do you know off the top of your head? There certainly was one. And if you Google the first back player in the NBA, you actually can get multiple answers Don't you find it odd that MLB stands alone in that regard?