Why don't they?
Because, what would be the point?
Spammers could easily just create another account. It would be too little deterrent for spammers.
To stop spam, something else, like having to manually approve posts would work. But that would increase the effort, and therefore, the required time mods have to invest to echojs.
There would be no point in banning him. He would just create another account.
Now that requiring that every post on echojs to be approved by an admin before it appears on the site, that would actually work.
But it would also mean a lot of more work for the admin.
"And when the night arrives, spammers come out of the sewer to share the same cryptocurrency crap."
This spammer has 60+ deleted news and keeps trying! Does anyone from echojs actually goes there and uses its stuff, to the point of keep trying every night?