Why didn't the SSS create powers like Tachibana Kanade (Tenshi) did? I saw Angel Beats a couple of years ago (can't really remember when), and I remember that Tenshi 


   created her powers with a software program.


So why didn't the SSS create powers themselves to fight her, if they were later on shown to be able to create weapons out of dirt?
If they remember how to do it, they can create weapons.

Also, at some point they can try to create things they don't remember (for example, the cannon at guild basement).

Probably, one or two people from the guild remember weapons, and they instruct the others.

For creating skills (power, abilities, body weapons), they need to know how to code and have a computer. They can get a computer from the computer room #1, but they also need the Angel Player software and a programmer (and apparently, only Takeyama knows how to do it).

Also, you don't know if the Angel Player is a software from the afterlife, or a software created by Tenshi. Maybe, the software itself is more difficult to create.

Lastly, if I remember correctly, Tenshi is the longest afterlife inhabitant.