Is my SEO hurt using this type of redirects?

I've seen many websites, specially social networks, allowing their users to have on their profiles a link to their own website/blog, but in reality they all are using redirects.

I wonder why are they doing this? I imagine it's because is a cheap way to get links with "valuable" anchor texts, so I decided to try it myself.

I'd like to make sure this is not going to hurt my SEO.

Side question, what is happening with my page rank when using window.location.replace(redirectURL)?

PS. I am sorry if anything I just said/ask doesn't make sense.