Section 12 would indicate otherwise.
Subsection (3):
>A duty to operate a service using proportionate systems and processes designed to—
>(a) prevent children of any age from encountering, by means of the service, primary priority content that is harmful to children
Pornography is included in "primary priority content".
Subsection (4) then goes on to say
>The duty set out in subsection (3)(a) requires a provider to use age verification or age estimation (or both) to prevent children of any age from encountering primary priority content that is harmful to children which the provider identifies on the service.
Subsection (5):
>That requirement applies to a provider in relation to a particular kind of primary priority content that is harmful to children in every case except where—
>(a)a term of service indicates (in whatever words) that the presence of that kind of primary priority content that is harmful to children is prohibited on the service, and
>(b)that policy applies in relation to all users of the service.
Or, on other words, if there is the possibility of people posting anything that can be considered pornographic, you must implement strong age verification.
And it's also not only targeted services. Yes, Section 12 says only applies to services "likely to be accessed by children", but if you read Ofcom's guidance that is incredibly, ridiculously broad.
To quote from their "Children's access assessments guidance":
>Even if your service does not actively target children or seeks to limit access to children below a certain minimum age, it may still be of a kind likely to attract a significant number of children.
And some examples of content types from that document that suggests you might attract a significant number of children:
* Art, music, singing, photography, videography, drawing, painting, cooking,
drama and acting, crafts, creative writing, beauty and makeup and fashion.
* Content about future careers and finance.
* Content about wellness, health and fitness
* Content enabling the development of new skills.
* Informal political commentary