It's just a default option that appears on NPCs, primarily used for talking to trainers or vendors or those guys walking on the street if for some reason you really wanted to right click--> left click instead of just hitting left click.
Been like that for as long as I can remember. I guess they did think it would be more useful at the time, dunno.
I have to ask this "maybe silly" question that I have always been wondering but never either had the energy or time to ask until now. How does the in-game NPC chat function work? As you see by the image below, sometimes when you get a pet to help on a mish, this "follow, chat appears rather than the "info" option.
If you click on chat, nothing happens or no prompt appears. Not sure if this was implemented back in the day when it might have been thought to be more useful or was going to be used for something else, then the dev's just decided to scrap this option but never removed the chat feature with the NPC, I have no idea? I've also noticed this sometimes by clicking on some random NPC within the game and I will get the Follow/Chat option. Can anyone elaborate more on this?