I think it’s more credulous lack of investigation than “mass stupidity” on the part of the media, leading to mass ignorance by a public that mistakenly depends on the press. An investigation of Andrew Wakefield (such as Brian Deer eventually did) would have revealed (using public sources) that Wakefield held the patent on a competing measles vaccine. Had the safety of the measles vaccine used in the used in the measles-mumps-rubella-varicella vaccine been called into doubt and replaced, the amount the trial lawyers (US & UK) paid him, would have been chump change compared to the royalties he’d have received.