Not enough people have needed/ voted for ELA.
The way this works is that there is a section in Socratic when you click the drop-down menu underneath the logo.
It should have a list of subjects, and at the bottom, there should be one labeled "What's Next?"
When you click on that, it will show you the subjects that may become one of the main ones in the future.
If you are passionate about any of these subjects, you may become a leader. (Make sure you have experience with this subject as well, I learned this the hard way!)
Once there are 7 leaders and they have created a great structure for that subject, it will become an official subject with a logo and everything!
If there is a subject you think should be a part of Socratic, and you do not see it under "What's Next?", then you can send in a vote for your subject at the bottom. Hopefully, other people will vote for it too, and it may or may not eventually become a subject.
If you have any more questions, here is a link to more information about this: Click Here for Another Explaination