At the same time, "On the positive side, Google has also gotten better in identifying high-quality content, and these days it’s not uncommon to see
amazing articles published on small blogs outranking high authority competitors with lower quality content."
Pros and cons of high content footprint:
1) User Engagement Metrics impact on SEO Rankings
Sites with a large content footprint gain the benefit of being "tested" for many more keywords on the first page of Google. This can be both a Pro and a Con.
If the content they're testing is good (meaning people click through, read the content, stick around the site), then it might "stick" on the first page for whatever keyword they're testing.
If the content is bad, then the content can get stuck on page 2, 3 4 etc. for months before getting a second chance at page 1.
In the context of a Q&A website, imagine the following example: Google tests a Q&A page with an un-answered question. If someone clicks through from a search, they are likely to bounce because they didn't find the answer they're looking for.
This would be a negative signal for Google, and this "root cause" of the symptom the author observed ("Google now penalizes domains that have a high content footprint relative to their domain authority").
One solution could be to "noindex" Q&A pages until there is at least 1 answer.
2) Google Crawl Budget and Indexation Status
The other "down side" of a large footprint could be indexation rate, also known as "crawl budget". For very large websites, Google needs to devote more resources to your website to keep their index up to date.
Newer websites with less authority simply get less crawl budget. Older websites with more tend to get more crawl budget.
If stack overflow adds 100,000 questions in 24 hours, then Google is still likely to index all of them and show them in their search results. However if
CapitalAndGrowth.org suddenly adds 100,000 questions & answers then it might take weeks or months to index all of those.
I think for a Q&A website this won't really be a problem because all those questions directly stem from user engagement, which drives other positive signals for Google.
This is more of a challenge for up-and-coming eCommerce websites with tens of thousands of products, or new directory websites (Yelp competitors) who have pages for every city and state in the world.
The only solution I've seen for these types of sites is to roll out their new pages incrementally. Instead of launching them all on 1 day, roll out the updates so you launch 10-50 new pages per day.