By contrast, I could be a digital marketer that has deep technical knowledge that allows me to spin-up and maintain my own high-powered (fast) environment on digital ocean to keep my costs at a minimum, sign-up for a free account and configure my whole site (or private blog network) to route through cloudflare, ensuring my website sits on the "edge", ensuring my website experiences as little network latency as possible no matter where in the world a visitor is from.
I can then register expired tld domains, and take advantage of previous registrant efforts and hard work to get indexed quicker using that domain directly, or 301 redirect traffic to an alternative domain/website.
Regarding email marketing, if you are generating revenue from your website(s) through email marketing, chances are you're not distributing that email marketing list
without using a 3rd party service, which isn't going to be hosted on your server (so not the same IP address).
Personally, I think there is too much conjecture around ranking signals, and how intelligent Google is. I'm certainly not saying that Google doesn't implement the things mentioned, but there are an awful lot of things bandied around as "fact" when from a technical standpoint, it wouldn't make sense to use it as any kind of ranking signal as it is too inconsistent or impossible to determine definitively one way or the other.
Ping times from different countries around the world using:
https://hostingchecker.com/tools/ping/
acorndomains.co.uk (not using cloudflare)
domainsaleshistory.uk (using cloudflare)