Michael Douglas is a great talent who makes a film his own. Drew Barrymore, on the other hand, is disposable. ie. ten a penny. You could replace her with any other average run of the mill actress and the film would be unaffected.
Very few famous actors/actresses are exceptional/unique. From Jack Nicholson to Jim Carrey to Robin Williams, they bring something to a film only they can provide. Likewise those with a look (Arnold Schwarzenegger), or a unique voice and delivery (Alan Rickman).
Ball park figure, I’d say close to 90% of famous actors are disposable. You could replace them with unknowns from drama schools, and the status quo would remain. One actor touched on this theme when lauding Daniel Day-Lewis:
"In this glittering cesspit we call the acting profession, there are plenty of rival thesps who, through sheer luck or happenstance, seem to have the career we ourselves could have had if only the cards had fallen differently. But Day-Lewis is, by common consent, even in the most sourly disposed green rooms – a class apart. Performers of his mercurial intensity come along once in a generation."
The like of Day-Lewis are always going to make it such is their talent. The others, which is the vast majority, make it via “luck of happenstance” (nepotism in the case of Barrymore).