If you “comment out” subareas in the Dynamics 365 sitemap or disable them with the XRM Toolbox sitemap editor, you should be aware that if you edit the sitemap with the Dynamics 365 App Designer, the disabled subareas will be removed from the sitemap.
Why is this a big deal?
The reason this matters is because it is fairly common to comment out standard sitemap links that you don’t want to roll out yet. Then when you need these features, enable them. Let’s say that you have Field Service installed in your environment, but you aren’t ready to use it. If you delete these links from the sitemap, it can be cumbersome to add them all back later. If you disable the field service group links, you can easily re-enable them when you want to add them to the sitemap. But if you edit the standard CRM custom app sitemap with the App Designer sitemap designer, these disabled sitemap areas will be removed.
Based on this behavior, I recommend that you don’t use the App Designer sitemap editor to edit the default Dynamics 365 sitemap. Only use it to create and edit sitemaps for new app modules–for the default CRM sitemap, use the XRM toolbox if you want to disable sitemap subarea links.