One of the techniques of writing in plain language is to use a conversational style – to write as though your reader is physically in the room with you.
But there are aspects of spoken conversations that should not enter your writing. ‘ums’ and arhs’ and ‘you knows’ are clearly out.
Sometimes when we speak with each other we include words that are not really necessary for the content we are delivering. These clutter phrases and additional words can be helpful in conversation to slow down information delivery, giving the hearer a little more time to process the ideas.
But this not needed when communicating using the written word. Readers can control their reading speed and the rate they encounter new ideas in a way that hearers can not.