Dolphin gets bug fixes and improvements every day, but the last official version release was in 2016.
I was wondering if update releases could be more frequent? At this point, it would make more sense to just download development builds.
Point releases (aka "stable builds") require a ton of effort and coordination to pull off. There are still some things I believe certain developers would like to see finished/fixed before that, and it's a huge time sink to get all of that on track. So, for the time being, something like Dolphin 6.0 is being put off. It'll come eventually, probably before the heat death of the universe. It's a slow process once it does start anyway.
You're correct about dev builds. They're safe and stable enough where there really is no point in not using them. 5.0 is old and slow in comparison to the latest builds, so we generally recommend the latest one from Dolphin's buildbot.