Reddit will comply with Australia’s under-16s social media ban, due to begin on Wednesday, but says it is “legally erroneous” and “arbitrary” in its effect.

The company argued to the eSafety commissioner that its platform was a source of information, not primarily social media.

Documents obtained by Guardian Australia reveal the company said it was “not centred around real-time social networking among young people”, but rather a “pseudonymous platform organised around sharing information”.

Reddit announced on Tuesday, one day before the ban was due to commence, that it would comply with the law. But in a post on the platform that confirmed the decision it also outlined its objections.

New users in Australia will be required to provide their birth date on signup, and existing account holders will go through an age-prediction model, Reddit said.

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“We’ll start predicting whether users in Australia may be under 16 and will ask them to verify they’re old enough to use Reddit,” the site said. “We’ll do this through a new privacy-preserving model designed to better help us protect young users from both holding accounts and accessing adult content before they’re old enough.

“If you’re predicted to be under 16, you’ll have an opportunity to appeal and verify your age.”

Reddit described the under 16s ban as “legally erroneous” and “arbitrary” in the post.

Documents obtained by Guardian Australia under freedom of information laws include a September letter from Reddit to eSafety in response to the regulator’s initial contact with Reddit to ask whether it believed the ban should apply to the platform.

In the letter the company argued it was not a social media platform as defined in the law.

“The sole or significant purpose of our platform is to provide knowledge-sharing in timely, context-rich conversations; interaction between end-users is simply an incidental step to enabling this primary purpose,” Reddit said in the letter.

Reddit is a “pseudonymous platform organised around sharing information in topic-based communities rather than personal profiles or social networks,” the platform said.

“It is not in keeping with Reddit norms for users to use their real names or identities on Reddit, as communities are not centred around real-time social networking among young people.”

Reddit does not promote real-time presence, friend requests or activity feeds that drive ongoing engagement, the company said. It said it was committed to collecting minimal personal information from users to preserve pseudonymity on the platform.

The platform pointed to the r/BabyBumpsandBeyondAu and r/AusSkincare subreddits as examples where Australians sought advice or product information.

“People also use the Reddit platform because it serves as the internet’s host of record on a range of sensitive topics, enabled entirely by its pseudonymous nature,” Reddit said, pointing to subreddits such as r/stopdrinking.

“These discussions highlighted to us that the Reddit platform enables knowledge to be sought, distributed, and discussed by the community,” Reddit said.

The Australian Financial Review reported on Tuesday the platform was preparing to launch legal action against the ban, but the company had not confirmed this as of Tuesday morning.

Following Reddit’s announcement, X is the only platform of the 10 initially named by eSafety as needing to ban under-16s users in Australia that has yet to state whether it will comply. The company has not responded to requests for comment. Its Australian regulation page stated “anyone above the age of 13 can sign up for a service”.