Edge has an uphill battle but “benefits” as being the default browser in Windows 10. This is providing that end users don’t try to avoid the ‘e’ browser (because of Internet Explorer).
Having the Edge browser only update with OS updates is a major problem. It is bad enough that it isn’t in their latest server OS (Windows 2016) and only exists in Windows 10. It being updated only when a new major build of Windows 10 makes it so IT and vendors will want to stick with other browsers (e.g. Google Chrome).
It is fine for an initial version of Edge to be included in Windows 10 if not already present (in the case of an upgrade). Allow the Windows Store and/or Windows Update to upgrade Edge with fixes and new features more often, outside of Windows 10 updates. Too many people are on varying Windows 10 builds (1607, 1703, 1709, and now 1803) and their are difference to Edge on each of these releases. Developers and support folks will take the easy route and simply point them to use the latest version of Chrome.
If Microsoft wants to make edge more relevant, it is time to update Edge outside of the Windows 10 release schedule. Oh, and ideally make it work on Windows 7 and 2016. But that is a different topic.