Some people are used to signing up before asking a question, others do not think that way and may forget important details after taking time to register. You can't make everyone happy...

Anyway, what is your actual question?

Pretty much every site on the web has a "sign up" form on the login page unless it's impossible for the public to sign up.

At bare minimum, some text indicating how to sign up should definitely be there (i.e. "To sign up, begin the process of asking a question and you will be offered a form to pick a username")

You don't even have to ask a question to sign up, but the signup form is hidden in there.

My question is who needs to see this in order to fix the problem.

Thanks for your answer FWIW, looks like you put in a lot of time. This was feedback for whoever manages this website.

The way it is now has been this way for several years now.

If Mozilla was going to implement the more traditional way of registering a account like some forum software has then they would have done so years ago.

Most people new to this site have a issue(s) they want help on and Mozilla would prefer people ask it as a new thread and not hijack an existing thread that has same or similar question. The more traditional way of registering would greatly increase the amount of using a existing thread hijacks upon first post. https://support.mozilla.org/en-US/kb/forum-rules-and-guidelines#w_posting-support-requests

Plus this Ask a Question introduces you to the Knowledge base https://support.mozilla.org/ during the process which may answer some or all of their issue(s) before submitting.

A small bonus is this has helped keep Spam threads and posts to a minimum. On the independent forums.mozillazine.org with the more traditional method of registering a new account, there have been more spam attempts vs legit posts by new members first postings each day.

Unless you have been around for a while many may not realize Mozilla actually allowed Guest posting during the first year. This was not the best idea then and certainly not now.

Mozilla is not significantly working on this old Kitsune platform anymore (unless that has changed in last few months). Early last year Mozilla actually moved the site to a Lithium platform that they had high hopes for but it had a number of issues and Mozilla then moved it back to Kitsune after a while.

Btw now that you are registered you can discuss about this in https://support.mozilla.org/en-US/forums/contributors as this Thunderbird section is for the desktop Thunderbird email client.