Immunity doctrines aren’t designed to protect against (and they aren’t necessary to protect against) meritless claims. Instead, they protect against *meritorious* claims, which is their main function. Immunity doctrines ensure that government officials can’t be sued even when they violate the law.
Fixing this also isn’t something that can be done incrementally. I will write an article on this someday, but a recurring problem is that jurisdictions pass an incremental reform allowing certain claims, and the judiciary responds by interpreting the reform to be as useless and limited as possible.