The kingdom is more supportive and they're in the bid for 2030 World Cup which is the major reason for the importance of bringing popular players into the league. There were discusssions that the kingdom wants Saudi Arabia Pro League to be competitive with the old English Premier and European Leagues, but that isn't the truth. Because it is a known fact, some things can't be changed in a short.
The presence of Ronaldo into Al-Nassr have given good reach to the league. Al-Ittihad and Al-Nassr were much on the race to win the championship. Rest of the teams too perform well, and the signing of players weren't disclosed. Saudi Arabia Pro League is trying to do the best and do everything in the global standard. The league have taken big list of players and the next season will give clear data on how big investment were made on the league.
To be fair, they don't really need to be competing with any other league in talent, the point is not to be "good", of course being good makes it easier but the point is to be viewed more, they have said this themselves. If they are one of the top 5 leagues that gets viewership, that's more than enough for them, they may not be even in top 10 leagues in talent, but if they are watched top 5 that would be more than enough.
Being there is not that impossible, if they keep getting more and more famous players, that will make people watch the games a lot more and that should result with them getting better eventually, famous players equals more viewers. Ronaldo made this happen and I think he is going to keep bringing more of his friends there for sure.