Why John Stamos failed to be a superstar after mega success of Full House?

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When Full House was aired on TV, I watched it from the very first episode. Uncle Jesse was my favorite character. Person like Jesse being so popular among girls still have heart for those 3 kids was great to watch. He was also a brilliant actor though I don't like his songs. I thought he will soon be a superstar in the big budget movies. But I just found him in a couple of movies and he failed to be a cine star. What can be the reason behind this? Anyone have any idea?