I suppose it's hard to miss what you never had and for some Windows 10 Insiders, this latest news will probably be received with a meh and a shrug.
According to a memo that has gone out to the limited number of testers with access, the sought after features of Sets has gone through its testing paces and the Windows group has enough telemetry to shut down the project for now and not bring it back until some later date in the future.
Sets is now offline -> Thank you for your support of the early testing we’ve done with Sets. Your feedback helps us as we continue to develop this feature. Starting with this build, we’re taking Sets offline as we ready RS4 for release. If you have been testing Sets, you will no longer see it – however, Sets will return soon in a post-RS4 flight! Thanks again for feedback, and we look forward to sharing new Sets features with you soon.
For most Insiders, the news lands with a muted response as Sets was released to only a handful of testers and only spanned the length of one preview release (not counting the 2.0 fix release). However, for those Windows 10 Insiders who had access to the feature in the previous 17074 build, this latest news puts them in a bit of a quandary as to whether or not to upgrade to the Sets-less new build. Not having tried it myself, I can't speak to the additional functionality Sets may have provided but judging from the engineering notes on the latest Windows 10 Insider preview, testers will be missing out on a lot of new features in preview 17083 as they cling to their build with Sets.