The creative writing world is full of people telling you what you should do and can do and cannot do and should not do and you should take no notice of most of them – probably including me.
The point is that it is YOUR writing, YOUR book. Did James Joyce take notice of CW courses about spelling and punctuation and did it hold back his career? Quite. For every single rule you will find a successful writer who has broken it. One of those I have come across more often than almost any other is probably ‘Show, don’t tell.’ Er, why? It entirely depends. On you, your writing, what you are writing, what works best for what you are writing…. Some novels show, some tell, some do both.