That is essentially correct Pete. When i registered for the new version of blynk, the registration wouldn’t allow me to use my active emails as I had previously registered to the old version(another point of contention).
I own 20+ domains and a number of them are setup as virtual table accounts, meaning that I could send an email to peteknight@mydomain or firstname.lastname@example.org and they would resolve to one mailbox. Virtually unlimited. I do this for spam reasons and I can identify the source of email abuse easier. I am scaling down and want to use a single domain with a limited number of valid emails. Thus the reasoning for wanting to change the registration email.
Considering another point, If I worked at CNN news (corporate blynk account) and my role and email changed to another another entity and position, I would loose all the streams, keys etc. that i created and installed on devices. At the corporate level this would be devastating.
I have worked in the internet business for over 29 years and I can confirm that not everyone uses gmail and more are transient than you may realize. I have advised customers to change their email when our barracuda spam filters simply cant keep up to someones account. Also it is common practice for scammers to use a valid email to spam, this is when i recommend changing your email, as no isp attempts will cure that!