I'm gonna explain it with an example:
In this episode I have 19 girls to id, and I'm not the only one interested in them. Now, think for a moment that instead of keeping the search in the thread, everyday I and the people who want to know the girls (lets say 5 more people, which I think it's a low number) are gonna do what you did, create a new thread with the same pic. So, this means we'd created 6*19 = 114 threads each day, all equals. Oh wait, lets count also the others episodes I have with threads (more than 40), which means everyday would be created aprox. 114 * 40 = 4560 new threads, all repeated. Yeah, 4560, more than 3 threads per minute. Do you think is logic to flood the forum with that?
Call it "stealing", call it what you want. To create that pics takes time, so I spend my time creating it to id the girls easily and to avoid the massive creation of different threads with the different girls. So yeah, when you come and do what I'm trying to avoid, and using my own image... making all I did worthless, well, it doesn't feel too nice.
After saying this, this is a free world, and I think it's not forbidden to create multiple threads asking for the same girl, so you can do whatever you want. But make sure you don't use my pics to duplicate my threads in Freeones, just get your own captures.