No one has had the longevity of idolism that Alonso has had, he has 2 world titles, both which came early in his career, and yet he is heralded as one of the greats and just needs the car, he's had the car multiple times since 2006 and has failed to convert. Struggling teams rarely progress with him in them, McLaren, Alpine, Aston Martin, none of them progressed with his presence.
The conversation for Alonso has a much longer time period to call upon than any other current driver, sure there are other drivers in the sport who could have the overrated conversation, but none as pertinent as the Alonso one.
Unpopular opinion I know, but lets look at Alonso's carree since he won the F1 WDC last in 2006. Championship victory in WEC 2018/19, alongside 2 endurance racing stalwarts driving a car in a team that had no realistic competition whereby the only race Toyota as a team didn't win was by virtue of disqualification. What else? Handful of F1 podiums and some what ifs.
There are some mitigating factors throughout his career, like with any driver, but when does 'bad luck' and 'unfortunate circumstance' become more a problem with the driver?