I assume it is so that websites don't abuse it to build search boxes for their own sites without showing ads? E.g. I can build a searchbox on mywebsite.com, an

I assume it is so that websites don't abuse it to build search boxes for their own sites without showing ads? E.g. I can build a searchbox on mywebsite.com, and if you type "hamster" I'll just query google for "site:mywebsite.com hamster" and return the results to you. That way, my site can be static but still have a search box, and google has all the work but gets no money.