Most managed environments only update the core WordPress environment. Not us we do the lot.
Not only the WordPress core but the plugins and themes if the authors have made it available. We even visually confirm the top 10 pages to make sure they are pixel perfect. We also provide virtual security patching if there is a vulnerability found in the wild with your site.
We also have white screen of death resolution and self healing micro services. Lets face it some plugins are just crap.