User Agent strings aren't used for feature detection, they're used for classification. As a developer, when you're trying to fix a bug reported by a customer, it helps to know exactly which browser right down to the patch version that bug shows up in so that you can try and reproduce the bug in the same environment.
> At Akamai, we use the User-Agent header at the edge and as part of many Akamai products for business logic
The post then goes on to describe several things that are expected to break (or would be breaking—if Akamai weren't taking steps on their end) since they rely on the value of client's User-Agent header, and it affects how they respond. It's definitely not just for being used at Akamai to help reproduce bugs in the same environments...
Akamai uses user-agent strings in its Bot Manager. They see what specific version of what browser you're running, then check certain characteristics of the request (eg header order) against a database. That isn't going to work anymore.
And good riddens. It makes the internet brittle and isn't especially hard to work around anyway.
I largely overstated that. Of course. However, my feeling throughout the entire post is that it was like they were announcing bad news about which they were not too overly about this because they based their optimization strategy on this. I was like "the world told you so".
Our goal of the post was more around educating our customers, who may not be aware of these changes, and these changes can affect their custom logic, if they depend on the UA.