Sometimes I yell at people like that, though I prefer not to. Another thing I've yelled at inexperienced people about is pulling by effort on the flat, instead of holding the cadence. The front rider mustn't slow in the gusts or going over little bumps because that totally screws with the paceline.
If I'm running the group, I make clear what the goal time is on the front, which is never over 3 minutes if we're trying to move the thing. Weaker people pull the same pace but shorter. If someone new to the group doesn't get that, I'll just come up and tell them, rather than yelling at them. So that's another thing to think about: if you have a strong opinion about something, you should also be strong enough to ride up and talk to the rider about it, unless there's some danger. If you're not strong enough to do that, maybe it's not a problem. If it's a rolling paceline, it's fairly easy to talk to anyone as they go by.