It’s like telling someone “your opinion doesn’t matter cause you’re ugly/old/young”.

A post is either relevant or not, regardless of when account was created.

On this thread there are multiple accounts created in the last few hours

I don't see the relevance of the account age as long as the person is engaging in a healthy discussion.

However, I have noticed that in other comment sections, such as those on „Der Spiegel“, some people attempt to dismiss the opinions of users with recently created accounts as well.