Plenty of people don't talk down to 5 year olds. That's an assumption you've made regarding 'explain like I'm 5'.

Ironically, that's what makes 'explain like I'm 5' so useful - it takes away the assumptions people have in their heads and forces them to use simple language and explain things from first principles.

It's quite powerful really. Richard Feynman was famous for being to explain physics in a way a layman could understand. Neil deGrasse Tyson does the same and people love it.