Here are the steps.
Step Zero - Ensure that one is logged out of the Battle net launcher, close the launcher completely, and ensure one is logged out of all of Blizzard’s websites (WoW, D3, SC-2, battle net, etc.).
Step #1 - Clear browser cache and cookies, close the browser completely, and then restart the browser.
Step #2 - Navigate to diablo3. com and use the links on the page to get to this forum and verify that one is still logged out.
Step #3 - Start the Battle net Launcher and log in.
Step #4 - Once the launcher is loaded, click on the blizzard menu (top-left) and select “Account Management”. This should spawn a new browser window or tab that loads the account overview page (account. blizzard. com/overview…).
At this point you are suppose to be logged into the forum because there is a cookie placed on your device, assuming you allow cookies. Without cookies all bets are off. I have accept cookies enabled. The only thing I should need to do is refresh the “General Discussion” forum page and the page should show me as logged in. This was the behavior of the prior forum. However, even though I’m logged into my account overiew (battle. net account) I’m still forced to click the login button on the “General Discussion” forum page. Clicking the Login button does not produce the login dialog, it merely refreshes the page with me shown as logged in because of the active cookie already on my device. No, I am not presented with an addition login request in the authenticator app. on my phone.
At the end of step #4, if I open a tab/window to shop. blizzard. com it shows me as logged in. So, I’m allowed to manage my account, spend real money on Blizzard’s various wares, but participating in the D3 community, a feature I’ve paid into by purchasing the game, has me restricted in various ways.
===============
According to TheTias (player in the General forum) the issue is by desire with respect to the compartmentalization of the sub-sites within the battle. net network.