The Modern vs Standard SharePoint site nav disparity

References:

• Jeremy Thake's article
• SharePoint blog on Communication sites
• ShareGate blog on Communication Sites

I have been struggling with this.
If you are an 'Explainer', then  Please explain/comment/opine/discuss on the following navigation disparity. 

A user logs into their office.com tenant using their domain account, and they have a full app launcher experience.

When a user selects the  "SharePoint" app  from the App Launcher tile, they are directed to the "SharePoint Home Screen" which is the new Modern landing page for Modern site creation, with News and sites that you are "Following".

The URL for this landing page is:   /_layouts/15/sharepoint.aspx 

Any sites that you have "Followed" show up here as well as "Featured" sites that an Admin has added (Edit)

There are two types of sites that a user can create from this page using the prominently links:
 The +Create button;
 The Team & Communication site cards

These 2 types of sites are both created using the prefix of "/sites/" or "/teams/" or whatever their SharePoint admin tenant setting "Site Creation"  has been modified to, from inside the SharePoint Admin console.

https://[tenant]-admin.sharepoint.com/_layouts/15/online/TenantSettings.aspx

A disparity in Functionality, URL and Navigation

The new Modern UI sites that are created in the above scenario are terrific, but there is a huge disconnect with the default SharePoint sites. 

Any of the above sites created using the new +Create button:

   1) Do not show in the SharePoint admin console on the right >

   2) Are NOT supported to open and customize in SharePoint Designer.

   3) They do not show automatically in any site navigation, 
        including the standard SharePoint site nav.

   4) Only these Modern sites are surfaced in the Graph and Delve.

The Standard SharePoint sites, at the base tenant [tenant].sharepoint.com have a totally different Site Creation mechanism.

To create a SubSite in here, you choose +New from Site Contents

Standard SharePoint sites have a Fully Customizable UI and can open in SharePoint Designer.

You can program the SharePoint home page as the starting point

See: https://techcommunity.microsoft.com/t5/SharePoint-Blog/Reach-your-audience-via-SharePoint-communication-sites-in-Office/ba-p/70079