Afterall most of the Oscar winners started in theater or do just as much live theater as they do in movies. Not to mention even in the debut roles in movies, many experienced theater actors (esp if they come from Broadway or England's theatre scene) are already praised in their first ever movie role such as Timothy Dalton's entrance in film in The Lion in the Winter.

It even seems having a theater background is almost a guarantee for a support even major role if nobody else has an lead role resume from a TV show or support roles in movies.

Is the quality of acting in theater esp the professional level that much greater?