I personally don't think there was any better chance for Dovi (assuming he is the rider many suggest) to win the title than 2020.
Marquez was out and Dovi was the expected one but he did not step up, others did.
Let us not forget that after Petrucci won in Italy (?) it was reported that Petrucci had made a statement that he would now assist Dovi to beat Marquez for the title, which many people attributed to team orders following a Dovi meltdown after being beaten by his team-mate, not unlike the Dovi meltdowns of the Lorenzo era.
All of that was 2019 and then 2020 and again Dovi simply did not deliver plus he was now 34 years old and few riders maintain their ability to compete as they get older, many have the mind but not the body/ability.
I would agree that Jack at 26 is not performing like a 33 year old Dovi would but this year Jack has won more races than Dovi did in 2020 (Dovi won 1) and matched the number Dovi won in 2019. Jack also has more podium finishes this year (3) than Dovi did the entire 2020 season (2), so perhaps they are not that far apart.
I mean, if we dont consider Miller good enough for a factory ride after 1 season, then it is clear why Dovi was dropped if we compare the numbers.
Total truth is the numbers surprised me when I just checked them - I did not realise how poor Dovi's 2020 season actually was