(Chrome on Win10) Why "Open as window" checkbox disappeared when creating shortcut of a page

I just got a new PC. One of the first things I do after installing Chrome is to create shortcuts of Gmail and Google Calendar etc as a stand-alone window and pin to task bar. I do it by clicking ☰ -> More Tools -> Create Shortcut.

However, I found the "Open as Window" checkbox is missing. No idea why. This makes the shortcut not a stand-alone window, which'll stack with the Chrome icon, which is not the desired outcome. How can I resolve this? Thanks!!

For the time being (Oct 2018), the answer is:

1. Create the shortcut in the way you mentioned in your question
2. Open chrome://apps
3. Right-click the newly appeared app and choose "Open as window", then click the app to run it
4. Pin to taskbar while it's open, if you want to
5. If you did 4, you can now safely delete the new shortcut on the desktop, but don't delete the new app in chrome://apps

Source: https://productforums.google.com/forum/?utm_medium=email&utm_source=footer#!msg/chrome/q3yliRThPPs/I0wPe7EnAAAJ