Here’s a muse; linking to external sites is probably one of the harder parts of blogging. Pages can go 404 and you won’t know exactly why, urls change even though they’re supposed to be immutable.
To blog while having pointers to disparate sources requires checking for dead links, and verifying that content relevancy hasn’t changed. The solution is to either archive everything (hard) or to not link at all (easy). High mutability is one reason why people take pictures of online content — it just works.