I'd assume if you weren't signing up, you'd probably look at like 10 profiles tops. A scraper is more than likely going to run through anything and everything it can grab links to (provided it doesn't leverage a very specific filtering mechanism for selecting profiles to scrape).

I could see the hit from a scraper being heavier than that of a typical user. There's also the potential that a user is going to click an ad for any number of reasons, there isn't that likelihood the scraper will.

I'm not anti-scraping by any means, but I get the concerns.