The only problem is when people decide to ignore the advice for some reason. Some Wow players seem to think that advice is an insult to their honor or something, and as such ignore it off principle. Either that or they know everything and couldn't possibly be wrong.

For instance, I was running Forge with three guildies, and two randoms. During every single trash pull with aoe, one of the dps would die. I noticed that the pally healer didn't have beacon on the tank, and saw that it was on them instead. As this was the strategy before they allowed overheals, I thought I'd inform them that they changed it and beacon on the tank would be much easier and keep us alive. The response was "um, no." When the dps all died before the first soul fragment, we decided to duck out of that nonsense.

Besides that, note that an undergeared person in your instance might not be there on purpose, as the random finder doesn't seem to treat the new dungeons differently than most. They're not trying to be carried, they just want the extra badges from the random.