You asked about saving a web link, instead of saving the link back to the index page when a user saves something to their tree. The index page will always contain a link back to the website but it takes one extra click to get there from an online tree.
We are trying to find a way to do both at the same time. The save to tree functionality on Ancestry wasn't originally set up to add a URL link when the user saves a record to their tree because we didn't anticipate this use case years ago when the tree system was being designed.
Saving a link to the index page was easy to set up. One of the advantages of doing this is that, if a publisher reorganizes their site and changes all the URL or structure, when we re-crawl it, we will get the new URLs and update the index. If it is just a URL link, it is more likely to be broken in the future.
We are definitely looking at ways to make the URL of the website more prominent in the source to make it even easier to get to the original website.