Was it common to own stationery in 1888 Whitechapel?
I imagine writing paper and other writing material were expensive to some people in those days. That might have some bearing in how likely it was for the killer to send letters to the press and keep sending them. He might have needed to practice a lot in writing those missives, and therefore needed to use a lot of paper and ink. I'm inclined to believe that the killer was a Whitechapel resident who might not have had a lot of money. Thus I'm also inclined to think that the real writer(s) might have had steady jobs that allowed them to buy lots of stationery. They might not necessarily have been in the field of journalism, but perhaps in fields that somehow created a desire in them to achieve fame through writing, especially if they worked in relatively menial jobs.
Many peoplel in the East End were illiterate or just had a very basic education. I doubt writing paper was top of the agenda, not exacly a necessity. No Letters sent out of the hundreds sent to the press etc have been proved to have been written by the ripper. Just the like sad trolls who use the internet today. Attacking women, insulting the police, claiming knowledge about the next murder, relishing gory detail.
Lower middle class people such as clerks, secretaries, etc anyone in an office job would have access to paper, and anyone could buy writing paper.upper middles and professionals would tend to have their own stationary with their addresses printed on them.