Key words there are "in the past." An RDS instance is not the sort of thing they're talking about at all. In one case study, they took a licensing process at Microsoft and reduced it from several weeks long to one minute, and reduced overall cost by 99%.
You could run everything on one system, but companies don't like trusting and paying whoever runs that one system, so mostly they run their own systems, send messages back and forth, and do a lot of cumbersome mutual auditing. That's exactly the sort of thing EY works on for a living.
There's absolutely no reason that (1) Microsoft licensing should have taken a month to begin with, that's madness, you can buy a license on their website in seconds -- so it was a process and policy issue, not a technology issue and (2) there's no reason that if you trust Microsoft and Windows to validate that license information that you can't trust them to store that license information alongside your receipt/proof of purchase. None. They're required to hold on to it by law anyways. And if they don't honor it (and they will) you can always sue them.
Who on earth needs to validate MyCo has a license to Windows other than MyCo and Microsoft? Absolutely nobody. And if you don't trust Microsoft to honor the license in the first place why are you doing business with Microsoft?
Now beyond that, EY. They're not selling blockchain, they're selling SaaS apps built on top of blockchain technology because they need to meet CTO/CIO buzzword quotas. Their SaaS apps could be just as easily run on, wait for it, AWS.
You could run everything on one system, but companies don't like trusting and paying whoever runs that one system, so mostly they run their own systems, send messages back and forth, and do a lot of cumbersome mutual auditing. That's exactly the sort of thing EY works on for a living.