A key part of a personal statement is showing what you´ve learnt from your previous experiences and which questions/research have they inspired in you.
In my case, going for the PhD totally comes from my great enthusiasm towards the subject of the graduate program I took last year (which was a no dissertation one, so no research on this matter). My previous work exp is also tangential. In this case, how could one show evidence of "previous experiences" that have inspired going for a PhD?