MLS’s growth strategy is predicated on the US rising as a football power in general and on America’s cultural cachet in general. It’s easy to see how MLS could slowly but steadily grow into a powerhouse by say, 2050. It’s not a strategy that will bear fruit overnight, but over several decades. A lot of MLS clubs have slowly become part of the sporting and cultural furniture in their areas.
The Saudis are trying to turn their league into a world attraction pretty much overnight. Won’t happen. Saudi Arabia has probably the least cultural cachet of any country on earth. Nobody will give a fuck.
Qatar attempted to turn PSG into a European powerhouse, a task that on the face of it should have been considerably easier than what the Saudis are attempting. PSG are in Paris, the city with more cultural cachet than any on earth, and signed Messi, Mbappé and Neymar. The rest of Europe treated them, and still treat them, as a joke.