It makes content creators miserable. Some of us just want to write good stuff and get traffic through Google, not build backlinks and be a SEO
* lack of https * lack of http/2.0 * lack of CDN utilization (aka lack of speed) * lack of Google backed advertising * lack of continuous updates * lack of inbound links * content not minimized * content not zipped
All contribute to a decreasing Google Page Rank (TM) over time.
But depending on the topic, "stale" may not mean much about quality at all. I've had a FAQ site about Tolkien's books online for at least 15 years now, and as it turns out he hasn't been publishing much lately (being dead and all). So apart from minor updates every few years when his son or other researchers publish new information from his drafts and notes, the site has been largely static for a decade or more. It's very good at its intended purpose, and it's hard to imagine what I could do to provide a steady stream of new content to indicate "freshness" without fundamentally changing the nature of the site.
I imagine that the same is true of a lot of sites out there, on a lot of topics that are far removed from the "breaking news" world.
http://firstmonday.org/article/view/833/742 (from 2001)
Google seems quite determined not to risk being seen as biased in that way.
I used to write for an amateur online magazine with product reviews and analysis of a certain industry. It wasn't big, but the content was good - not just in my opinion, I was told that many times by various readers. In ~2005 we routinely were #1 to #5 in searches related to the products we're covered. Today I often can't find new articles from that website even when I use the exact title as the query. The website is minimalist, fast and has no ads. The articles are extensive and well-conceived. And yet they are buried several pages deep under piles of single-paragraph stub "reviews" on more popular resources.
I assume the same thing happened/happens to a lot, maybe most small-scale content creators these days. Clickbait rules and content doesn't matter nearly as much as the number of incoming links. You can no longer rely on search engines to get you traffic and need to constantly self-promote on other websites (e.g. social networks).