There are a few reasons people recommend it.

1. Your tastes change over time, especially if you are a ewer smoker and still trying new cigars.

2. Cigars smoke differently at different levels of rh, different stages of their fermentation cycle, etc.

3. It's usually good to try new things at least twice. Not just cigars.

That being said it's up to you to decide if the advice of stashing some away to try later makes sense to you. Was the cigar you didnt like harsh and off putting, or did you just not like the flavor profile? Time usually helps get rid of that harshness, however if you just don't like certain flavors, that might not change.

For example, I don't like the flavor profile of most Sun Grown habano wrappers. I know trying thr same cigar later won't change that. However if the cigar just seems a bit harsh and gives me that ammonia type taste, I know it might be good to try again later. But who knows, I may develop a liking for those wrappers I used to not like.

In the end it is your choice. We can only make recommendations and it does not work for everyone. Smoke what you like. Feel free to ignore a cigar if you didnt like it that first time. It's all up to you.