Substack has attracted a number of high-profile writers to its newsletter platform — and it hasn’t been a secret that the venture-backed startup has lured some of them with sizable payments.

For example, a New Yorker article late last year identified several writers (Anne Helen Petersen, Matthew Yglesias)  who’d accepted “substantial” advances and others (Robert Christgau, Alison Roman) who’d started Substack newsletters without striking deals with the company.

However, a number of writers publishing via Substack have begun pointing out that this strategy makes the company seem less like a technology platform and more like a media company (a familiar debate around Facebook and other online giants) — or at the very least, like a technology platform that also makes editorial decisions which are subject to criticism.

Last week, the writer Jude Ellison Sady Doyle pointed to writers like Yglesias, Glenn Greenwald and Freddie de Boer (several of whom departed larger publications, supposedly turning to Substack for greater editorial independence) and suggested that the platform has become “famous for giving massive advances […] to people who actively hate trans people and women, argue ceaselessly against our civil rights, and in many cases, have a public history of directly, viciously abusing trans people and/or cis women in their industry.”

Doyle initially said that they would continue publishing via Substack but would not charge a subscription fee to any readers who (like Doyle) identify as trans. Later, they added an update saying they’d be moving to a different platform called Ghost.

Similarly, science journalist and science fiction writer Annalee Newitz wrote yesterday that they would be leaving the platform as well. And as part of their farewell, they described Substack as a “scam”: “For all we know, every single one of Substack’s top newsletters is supported by money from Substack. Until Substack reveals who exactly is on its payroll, its promises that anyone can make money on a newsletter are tainted.”

Substack has responded in with two posts of its own. In the first, published last week, co-founder Hamish McKenzie outlines the details of what the company calls its Substack Pro program — it offers select writers an advance payment for their first year on the platform, then keeps 85% of the writers’ subscription revenue. After that, there’s no guaranteed payment, but writers get to keep 90% of their revenue. (The company also offers legal support and healthcare stipends.)

“We see these deals as business decisions, not editorial ones,” McKenzie wrote. “We don’t commission or edit stories. We don’t hire writers, or manage them. The writers, not Substack, are the owners. No-one writes for Substack – they write for their own publications.”

The second post (bylined by McKenzie and his co-founders Chris Best and Jairaj Sethi) provides additional details about who’s in the program — more than half women, more than one-third people of color, diverse viewpoints but “none that can be reasonably construed as anti-trans” —without actually naming names.

“So far, the small number of writers who have chosen to share their deals – coupled with some wrong assumptions about who might be part of the program – has created a distorted perception of the overall makeup of the group, leading to incorrect inferences about Substack’s business strategy,” the Substack founders wrote.

As for whether those writers are being held to any standards, the founders said, “We will continue to require all writers to abide by Substack’s content guidelines, which guard against harassment and threats. But we will also stick to a hands-off approach to censorship, as laid out in our statement about our content moderation philosophy.”

Greenwald, for his part, dismissed the criticism as “petty Substack censors” whose position boils down to, “because you refuse to remove from your platform the writers I hate who have built a very large readership of their own, I’m taking myself & my couple of dozen readers elsewhere in protest.”

But when I reached out to Newitz (a friend of mine) via email, they told me that the key issue is transparency.

“If Substack won’t tell us who they are paying, we can’t figure out who on the site has grown their audience organically, and who is getting juiced,” Newitz said. “It’s blatantly misleading for people who are trying to figure out whether they can make money on the platform. Plus, keeping their Pro list secret means we can’t verify Substack’s claims about how its staff writers are on ‘all sides’ of the political spectrum.”