Only way they can grab your IP from these boards is if you clicked a link or loaded a scraper image. The only real purpose to getting an IP address is to ddos them. For sites using it for moderation, they use it for identifying who someone is, but they already have that information so they wouldn't need to use any of those methods. But, whatever. I just find using proxies is very inconvenient, and on these boards many of them are banned since people use them for malicious purposes.