I like to not overthink some things. I feel like there is a very simple explanation to this.
Republic Wireless has it set up to use one single login / account for all the different parts from the main My Account, here in the forums, in the Help section, and store.
This is called a single sign on system. This is useful because all the different parts are running different software. My Account and store are on different platforms most likely propriety, the forums are running discourse, and last time I checked, help is using zendesk.
Each of these services checks in with the central login server and the central login server returns the result saying ok with your unique account. None of these sites have an “auto” login which is why they require you to press the login button.
So yes, logging in doesn’t automatically log you into the other but also yes, they are the same account technically.