Based on the 5.x docs, I'd vote feature (emphasis mine)...
"About watchOS 5 Updates
watchOS 5 brings you new ways to be more active, stay connected, and monitor your health with your Apple Watch including Activity competitions, automatic workout detection, Yoga and Hiking workouts, Podcasts, Walkie-Talkie, new watch faces, an updated Siri watch face, and enhancements to notifications and the Heart Rate app."
Did you check the latest beta release notes to see if it's mentioned there?
Currently on the download page for watchos 5.2.1, there is a link for release notes.
That link takes you to the 5.2.1 Beta 3 release note page.
That page references xcode 10.2.1 release notes.
and watchos 5.1.3 release notes
and watchos 5.1 release notes
and watchos 5 release notes
Curiously there are no release notes for watchos 5.2.1 beta-anything.
Additionally the Apple feedback app on IOS, only shows my iphone, and does not show my apple watch;
both of which are on beta software. watchos 5.3.1 beta 3 and 12.3 beta 3
Granted these are not big issues, but the absense of release notes, and the inability to report
the problem with the Apple feedback app, seems to show a bit of sloppyness eh?
If you're asking if betas are sloppy by nature, sure, I'd be tempted to agree.