Well, there are times that those fishermen are simply talking to one another, and yes, your point would hold true, they'd be butting in. But, there are times they've flagged someone down to ask about the fish, or to tell them they should be fishing in the lake too. At which point, someone may give their opinion about the lack of fish. Or, perhaps they're a fellow angler, casting a line into the same lake, and they may tell them it might make sense to put a hook on their line. Or to not eat the boot they reeled out.