Betting as a major sponsor and league endorsed? Yes, very new.

We've come a long way from the black sox and Pete Rose being banned for life over gambling

https://en.wikipedia.org/wiki/Black_Sox_Scandal https://en.wikipedia.org/wiki/Pete_Rose#Permanent_ineligibil...

Legal sports betting via app which turned gambling into a casual activity for hundreds of millions of new players. These apps made a market that previously placed 4 billion in bets to 125 billion. This is very new.

Their rise and market is so large that only 5% of sports bets aren't placed through one of these apps.

Online/mobile sports betting is relatively new, was only legalized in the last decade. It’s grown massively in popularity

Legalized, league-approved sport betting is new-ish (2018). And sports betting has grown 25x since then.

Not sure if I agree with OPs take though. It might just be that baseball is a traditional, conservative game and they are hesitant to change it. maybe that's why they're just using robo umps for challenges, and not for every pitch, which would be easy to do and would further the all-about-betting theory.