Imho, the problem with Lighthouse (and Pagespeed before it) isn't that they're not perfect, it's that they assign scores/grades.
When Google assigns a score to something, people understand it to mean highest score = best and start optimizing for the grade Google gives them, not for performance and user experience, which the grade is supposed to represent.
It would be more fruitful to list the issues and their severity but not add overall scores, because scores change the objective from fixing the problems to getting high scores. They occasionally also have the have bugs where they will punish something with a worse score that is actually an improvement in the real world, discouraging people from doing the right thing ("I want my site to load faster, but Google is buggy and will rank me down if I do").
When Google assigns a score to something, people understand it to mean highest score = best and start optimizing for the grade Google gives them, not for performance and user experience, which the grade is supposed to represent.
It would be more fruitful to list the issues and their severity but not add overall scores, because scores change the objective from fixing the problems to getting high scores. They occasionally also have the have bugs where they will punish something with a worse score that is actually an improvement in the real world, discouraging people from doing the right thing ("I want my site to load faster, but Google is buggy and will rank me down if I do").