I agree with you however there is the point of the person in question having already established themselves.
The new friend with the once-tainted name already has a personality/life-experience they can use to enforce your new view of that name.
A new baby has no self identity as yet and will be largely shaped by the parental interactions. As a parent, I didn't want my poor perception of a name to negatively affect in any minute conscious or unconscious way how I interact with my newborn child.
Extreme? Yeah. But parents tend to get a bit extreme on some aspect or other when it comes to their kids and I figured that - as you say - it's just a name. If my extreme is to simply rule out names I don't like, then that's not so bad.
And yet it seems that so few realize what a poor reason that is to avoid a name. Your perception of a name is not permanent. In fact, your perception of a name is quickly overwritten when you are closely associated with someone of that name.
You'll forget all about that person you don't like if someone close to you shares their name. The person close to you owns it now, at least in your mind.
This is not a judgment of the parent commenter. Everyone has a right to name their children as they choose. I just wish more people noticed how fluid their perception of a name is.