Action?

Only moderators can delete other people’s comments. Should we do that in such cases?

No. This would be minimum as rude, as you think the comments are. And imo it would be a misuse of your admin super powers.

Where's the difference?

You're expecting users that have some reputation to be wise enough to get around it and be friendly. But they aren't wise enough. This will evolve over time. It's just another step closer to become a "knowing" member. And therefore they are allowed to make failures - like humans just do often. It's simply said "part of the process" to become a valuable member of the platform.

The steps

Just from my personal experience, there're different levels a user has to go through:

• Interested
• Learning the basics of the system
• Doped by the system
• Answer spree
• Frustration (others not willing to learn/not excited about the system)
• Anger
• Patience coming back
• Feels like part of the system
• ...and here it splits: User leaves (Angry on amount of dump questions) or User tries further (Mostly User joins chat)...

And from looking at how many good users we already lost, I'd say it's more important to try to keep mid-rep people active on our page, than to be unfriendly.

Advanced Users

In some casessome cases I fully understand why people get angry and stop repeating the same comment on every question. There's just too much frustration potential out there. When you take a look at our "New Questions", then you see that most of the actual questions are from low-low-rep users. And some of them are really trying hard to not learn using the WYSIWG editor (you already use TinyMCE in WP, folks!), adding tags like wordpress.org and wordpress.com as only tags to a question, etc., etc.

Conclusion

So if you really want to take action, then try to get those people into chat. Talk to them, let them feel like they're in a warm, cosy and welcome place. Then tell them, why we're trying to be friendly to new users ¹⁾.

^{1) Which, in most cases, makes exactly no difference.}