If first 4k digital video camera was released in 2003, then why did movies keep being shot on 35mm films till early 2010s?

If first 4k digital video camera was released in 2003, then why did movies keep being shot on 35mm films till early 2010s?

If first 4k digital video camera was released in 2003, then why did movies keep being shot on 35mm films till early 2010s?
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