Do you have any good references/example/docs/keywords about the difference between setting up and running "a fully pull-based Ansible system" compared to "centrally-controlled push-based systems"? I'm fairly certain I'm doing what you'd call "centrally-controlled push-based Ansible", but I'm in the planning stages of formalising and operationalising our ongoing configuration management policies, SOPs, internal docs, and dev training - I'd love to know just how I'm "doing it wrong"...
(Note: we are not even in the same universe as Cloudflare, fleet size wise. Think perhaps a few dozen hosts, not thousands or tens of thousands. We've only just barely embraced the "cattle, not pets" stage here.)
I never had ansible scale through more than 100 servers. Its design assumes things will mostly work. Above a few hundred servers, things will fail all day every day.
Whereas I have seen salt easily manage 6000+ servers.
The fact that Cloudflare sysadmins were desperately chasing Salt logs between minions and masters in recent memory is a shocking failure of imagination (or investment) on their part.