Copy machines were always busy at the law office. Whatever you wrote, you needed one copy for opposing counsel, one copy for chambers, and one—if you were feeling reckless—or two for your own files. If you ran out of plastic toner, you were lost. Without copies to take to the Clerk’s office for filing, it was as if your work had not been done. Nowadays, the copiers are mostly silent. Filing at the clerk’s office is electronic only.
Paper has its own demands. You have to do something with a pile of documents. An email can easily be ignored; an email may be dumped into a spam folder only to expire after a month without anyone ever knowing that it was there.