How does SOP apply to anchors ?
When we link one website to another website. For example, sitea.com is linked siteb.com.
<a href="http://siteb.com"></a>Whenever such hyperlink is visited. The browser always loads the response in new context(tab/window). Via this the browser makes sure that there is no data leakage between sitea.com and siteb.com.
In simple terms, The response loads in a new window/context. The originating site is replaced by the accessed site.
Hence, any site can link any other site, but can't read the response