I have no idea what this is. All I know is that we should stay away from unknown things. 99 percent of them are scam. This may be one of the rest, but I suggest you be careful.
I have no idea of this too but as for reading some valuable comments, I understood on how this is possible and happening. Read this quote;
They use it to save gas fees and save time. By doing this so called self-drop, the developer don't have to manuall add/send tokens to the participant. However, this can be abused. Eg: someone can use 10 address to claim the tokens.
IIRC some succesfull tokens use this method to distribute their tokens, such as SCC.