One possible explanation for this is that psychosis
may lead to longer periods of restricted activity and opportunities
to use cognitive skills, leading to a decline over time.
Against this, other studies assessing individuals with psychosis over 10 years found no worsening of deficits after illness onset with some evidence that any progression may be because of medication or lifestyle factors. Further complexity in assessing cognition over time comes from individual heterogeneity, which may be obscured when assessing group means, as well as the potential for those who make good recoveries being underrepresented in studies with longer follow up periods.
I feel like these relevant points using your cognitive skills, get medication right and living a healthy life can literally be the impact cognition wise. I also sort of feel that there is this myth of a schizophrenic person who has fully recovered and there are different stories where some of these people make full recoveries. I think the self filtering presented by the later quoted observation is also relevant in the context of the forum community.
Ergo if schizophrenia does not define you as a person then simply you don’t feel defined by it. The attachment and need to relate with others around it as a space and place of discussion is therefore reduced. There are probably a under representation of people who make full recovery since after that point they cease to care about that experience and since they have moved beyond it because of the stigma associated they don’t necessarily want to talk about. Still rare but probably less rare then is apparent on the surface