Sharepoint - Can't deploy SPFx Extension tenant wide
May 2019 Update:
Tenant Wide Deployment for SharePoint Framework Extensions is supported for application customizers and for List View Command Sets in SPFx 1.6 and later.
Tenant Wide Deployment of SharePoint Framework Extensions
You can't deploy SPFx extensions tenant wide. Each of the extensions (application customizer, field customizer, and list view command set) use Features to associate the extension with the component the extension is targeting. Deploying tenant wide (or site collection wide if you're using the site collection App Catalog) bypasses Feature activation so the extension will never be associated with the target.
If you look at the getting started tutorials for each of the extensions you'll notice they are not configured for tenant wide deployment.
