> which isn’t really true anymore. For most websites, the majority — not just the plurality, but the majority — of visitors arrive by following a link inside an email or an app
I highly doubt this is true, unless your definition of "app" includes "web browser".
If your traffic is mostly links from social media, it may well be accurate - up to orders of magnitude more folks are using Facebook/Twitter/BlueSky/LinkedIn from the mobile apps than from desktop browsers