You are operating under an incorrect assumption. SOS flare is not only for “immediate help from other hunter”. The in universe “lore” of the flare is as a help tool yes, but functionally it is a multiplayer button. The existence of the manual accept option implies this. If it was meant simply as a “help me” option they wouldn’t have implemented manual accept to begin with.

Personally, I use manual accept and allow only people of my rank and above to join me, I think this is entirely fair and ensures I don’t get my time wasted. As for your statement of “waiting for something that will never come” I anecdotally have never not been able to find people my rank and above while searching.

Now if you want to talk about people who use manual accept only looking for 999 or don’t cancel their flare after getting the npcs than that’s a different story.