It seems the Saudi league isn't as boring as before. Since Ronaldo's move to Al-Nassr, the league has become much more exciting and has attracted a lot of attention, making it a truly different league. Several top players, especially this season, have started to be more interested in moving to Saudi clubs. While it's certainly not the average player, their salary also plays a role in the attention.
I also think that the attraction of some players who once shone in top European leagues to the Saudi Arabian League is due to the high salaries and the large number of fans who have started moving there to see Ronaldo. This is undeniable, as the Saudi Arabian League has now become famous throughout the world and continues to attract players no longer needed in European leagues. And I hope the Saudi Arabian League, which will resume at the end of this month, will provide even more surprises from the start.
It is about the salaries and that is it. The fans don't matter, I think if a club from a small county would offer players a billion a year, they would go everywhere. Ronaldo would go to Iceland if a club could pay him more than Al Nassr. There is so much talk about the culture and the fans and how players are interested in it, but that is wrong. See how Jordan Henderson went to Saudi Arabia for the money despite his position towards the LGBTQ community. It doesn't matter once the salary is high.
The Saudi Arabian league is so famous that players who are about to end their career choose to go there. To me it looks as if it is not so famous like you describe because otherwise the best players would go there and become stars there, but that is not how it works.