Probably single handedly ruined mainstream movies in the 80s
... inadvertently
Spielberg was so popular in the 80s that his movies spawned so many ripoffs.
ET was remade as Mac and Me (unfortunately not about macaroni and cheese); Indiana Jones spawned countless ripoffs (treasure of the 4 crowns, king solomon' mines). The problem however came when filmmakers tried to copy that patented Spielberg magic and inevitably fell on their face. Spielberg had an incredibly unique touch that made movies like ET magical. He could suspend your disbelief enough to make almost anything entertaining. When everyone else tried to copy that, they made terrible movies.