Congrats on never having a clipless moment, and the fact that you've never had one probably means you don't understand what it entails. Its not due to a lack of bike handling skills, but rather due to adaptive memory. For someone who has been riding all their lives with platform, the whole act of swinging your heel outward to remove your foot from the pedal is very foreign: usually you lift up and then put your foot down. Its very instinctive when you're used to riding platforms and when you delay till the last second to put your foot down your immediate reaction is to lift up, only to be reminded that you're using clipless and end up tumbling. Once you become accustomed to using clipless then pivoting your heel outward becomes instinctive.