I think I understand the point you are trying to make, that customers who are utilizing Netlify DNS Management are unaffected because reasons, but this is phrased in a way that implies that it is your users fault for this downtime because they didn't chose to use your related service.
Our current solution for the free/self-serve tier of Netlify has been to rely on Google's load balancer product to give people a stable IP pointing to a highly available solution. In light of recent issues, our team has setup a new permanent IP for A records (75.2.60.5) backed by a different solution, but due to the way DNS providers with no ALIAS record support work, it does require our customers to manually change their A records.
I totally get that moving DNS providers is a big deal and we want to give the best experience we can regardless of what provider you're on, but we have to work within the technical limitations of those providers and it's the nature of things that we do have more options to deliver a completely seemless experience when we operate both the DNS and the edge layer for customers.
We do offer ALIAS records between Route 53 hosted zones, and this capability is open to providers such as Netlify. We’d be happy to have customers ALIAS to a hosted zone managed and updated by Netlify. It sounds like your IP addresses are relatively stable, keeping these in sync doesn’t sound like it would be a big deal, and would give you a lever you could pull to change your customer DNS quickly in an event such as this. You could also configure health checks on your own DNS records, which any customer ALIAS records that point to your DNS records in Route 53 would inherit.
If you’re interested in going this route, please contact me at alecpete <at> amazon <dot> com.
Auto-refreshing the popular records in the background before the TTL expires to help smooth over any temporary issues?
Other big name DNS providers have ALIAS type records. I imagine according to the SLA, AWS Route 53 is still "available", even if it can't resolve a "target address record" (as the ANAME draft calls them) but Route 53 is still able to respond.
Some folks still choose to use this way, some have no other choice for various reasons and some don't care/comprehend the potential pitfalls. I do believe most users avoid using a root domain name for their website.
This is where you're definitely wrong.
I would personally imagine that any individual or SOHO business hosting their website on GitHub/GitLab would just buy "MomAndPopShop.com" and point it there. I guess I don't know off the top of my head how many of those sorts of places on the web still exist...