I'll have a stab at an answer. I think there's a range of reasons.

These magazines are produced by people will the skills, knowledge, resources, and contacts to produce a physical magazine. The southerly is produced by someone who was at the last indie paper to shut down here in Albany.

It's a side hustle. Get some advertisers to pay you to put their ad in a magazine at cafes and wherever else.

The online distribution just isn't relevant to these producers. They won't ever get any revenue from it. They're not interested in increasing their online readership. They don't know how to produce websites, because their skills and experience are in print.

In some ways, making their content available in a shareable way, like a blog post, makes it ripe for posting to facebook, which will ultimately reduce their readership.

Allowing you to see their production in a pdf viewer is a concession that allows you to show someone else some article you read at the cafe or whatever.