Any site feature may be abused by a few. However I think the gear list serves a purpose other than "showing off" (though for some it might serve that purpose also).
The gear list gives a general indication of the orientation, brand familiarity (also potential brand loyalties) and experience of each member. If someone is asking about the Canon R5 and their gear list is all Pentax APS-C dSLRs, one might give different advice than if their gear list is a Canon RPb - for example.
Similarly, if someone is recommending the R5 over the RP and their gear list is all Pentax APS-C dSLRs, one might give their recommendation a different interpretation than if they seem to be highly experienced with Canon R-mount systems.
IOW, it's a way of adding insight that gives some context and maybe nuance to the discussions.