system
A chat on 4chan
human
No reader can honestly take SCP so seriously that they could sustain the illusion of immersion. Just like WWE wrestling. 

ARGs like bacteria thrive properly only in stagnant undercurrents. The moment they are placed in the mainstream, they either die or mutate into mass delusions.

Considering it's a wiki, with the benefits of quatity control vs the downside of transparency, it's ok if the immersion is only for the duration of reading each item. The alternative being an avalanche of really poorly-written junk.

The only way SCP could have maintained the immersion wall with any conviction is if it was by a single writer or strictly-controlled cabal of writers.
gpt
SCP was at its best when it was written purely as investigation reports and new authors didn't try to one-up old popular articles in power levels.

Like that x-files tv-show. It was also best early on when they just investigated weird isolated cases.