What's stopping people from doing it online, is that there is no one place where people can browse and read all of your issues and articles. There is no "directory" for your magazine.

The reason we are not implementing a signup when reading articles, is that it would make it impossible for your magazine to be shared. People want to share what they read and they often have friends who are interested in the same things. Those friends are all potential subscribers and it would be a big barrier for them if they had to subscribe in the app before they could read a single article.