I guess they were trying to do multiple stops which is fine but updating the address everytime isn't the right way to do it. They could've put multiple stops when they placed the request. I wouldn't sweat it. It wouldn't have made a significant difference pay wise.
It was probably a pax who didn't know better, or who thought they were beating the system by adding the new drop off locations one by one. Either way as an independent contractor you can end the ride at any point. I don't know that I would but I do know that if I were to decide once I reached the first destination that the ride was done regardless what the app was telling me I wouldn't have any qualms about it. That said I do not like multiple stop rides. I just do not. If you want me as your for hire private driver you're going to pay a hell of a lot more for it than I'm getting paid on the app.
People have a hard time with the add a stop function, and having helped a rider through it the other day, I can attest that it's rather hidden and counterintuitive. Basically, just a plus sign next to the destination that you don't realize until you hit it will open another box to type a a second destination into. So I can see how these guys would work it that way. As other have said, I don't think it affects your pay.
I did have someone scam me the other day on Lyft. Short trip, he adds a second destination on the way, and now the original destination is just a stop. He says he needs to go in Walgreens and get some beer and then head home. I wait a few minutes then notice him leave the store and just walk away. Stupidly, I then cancel the trip, instead of tapping through the boxes that would've acknowledged the stop and then ended the ride with me getting what I should've gotten. I end up getting zero, and after waiting 5 days, Lyft finally messages me back that there's nothing they can do about it. So apparently the scam is to hope a driver is as stupid as i was and cancels at that point, making it a free ride for the rider who slipped away. Probably should've known -- picked him up at one of those blood banks that pays for donations.