How to stop Terminal from starting minimized in the Dock?
I'm using macOS 10.12.3 and Terminal.app Version 2.7.1 (388) and I don't see the "Hide after opening" checkbox option mentioned in the answer to the question you linked either.  

From the Terminal.app >> Preferences::Profiles pane, look below the list of profiles. In the gear icon menu you can export your current profile in the gear settings menu options. Open the exported profile in a text editor and you might be able to find the setting which is causing this behavior.



You could also try "restore default profiles" or simply rebuilding your profile from one that does not minimize at launch.

------------------UPDATE  

If "Restore Default Options" doesn't work AND you are having this problem with all the profiles you try, it might be helpful to post your exported profile settings in your question.  

Also, do you know which shell you are launching into?

To find out, enter this into your Terminal command line:

echo $SHELL

I am using the "Default login shell" and echo $SHELL reports /bin/bash

Are you using the "Default login shell"? You can find this setting in the Terminal.app >> Preferences::General pane:



Please post your OS and Terminal.app versions in the original question.

Also, after changing your profile, have you tried logging out, restarting and logging back in then verifying that the profile change is still in effect?