Here's a workaround you can use to disable the Start Page from reopening after a solution closes.

The steps to follow are:

1.Close all instances of VS & Run Regedit

2.Select HKEY_LOCAL_MACHINE

3.File -> Load Hive…

4.Open %LOCALAPPDATA%\Microsoft\VisualStudio\15.0_<characters>\privateregistry.bin

5.Enter a name like “MyVSHive”

6.Navigate to HKEY_LOCAL_MACHINE\MyVSHive\Software\Microsoft\VisualStudio\15.0_<characters>\StartPage

7.Create a new dword with a non-zero value like so:

"DisableOpenOnCloseSolution"=dword:00000001

8.Select “MyVSHive” and then go to File->Unload Hive…

9.Restart VS

Now, on closing a solution, the Start Page will not autopen.

Please note that resetting your settings will cause this setting to be reset and you will have to run through these steps again.

Thanks,

Praveen [MSFT]

Since MS hasn't changed this behavior (as of Update 2) and shows no signs of budging, I'll reiterate my comment from April 8th as a "solution":

I added an "Auto-close Start Page" option to my (free) Menees VS Tools 2017 extension. The option is off by default because I don't want my extension to change VS behavior for everyone (since people primarily use it for other things), but this option is available now to those that want it.