Population density helps a lot with that in the UK at least. And even people coming to Brighton or a London event from Germany for example could realistically consider an international train or £50 budget airline.
I imagine this is another case of "technically correct" - Google is using something correlated with that, but not that exactly. See also siteAuthority vs. Domain Authority 😅
Having a loyal audience isn't necessarily the same as having a big demand for your brand - afaik they were never getting a big ratio of branded traffic relative to their overall SEO profile.
I didn't look at individual sites but their DA:BA ratio is huge.
The biggest pieces are assessing what Google considers to be your branded terms, then measuring demand over time for those terms.
moz.com/learn/seo/brand-auth…
And naturally, I did my best to pick control periods for the brand:links ratio HCU results. Which produced the expected non-replication of HCU behaviour.
Full data: moz.com/blog/helpful-content…
But don't get too excited - a 12% gain in one update isn't worth much when you're 80% down YoY.
This is based on about 500 sites which are very clear HCU losers, btw.
I had a theory from the Google leaks: The HCU is not about content.
It's about brand:links ratio.
I've looked at the last 3 updates, ~2m keywords, and tens of thousands of sites, trying to prove it.
Results are a lot clearer than I expected.