Precisely. Recruiters ask to ensure that there is at least a "ballpark" match up before proceeding -- it would be a waste of your and the hiring team's time to interview you if your salary requirements are outside of their budget.

I can understand how some may be hesitant to offer this info up since it is considered sensitive in many cultures, but I have no problem doing so. I understand that there is no malicious or malevolent intent in their request for this info (at least, there rarely is...).