Being completely out of the loop, when and why did that happen?
It was just over a year ago, and the reason was a handful of people constantly starting brand vs brand debates in technical threads, about why x is superior and y can never compete or why you have to value one use case over the other.
Basically it spread from the Industry forum which has always been horribly tribalistic over to the tech forum.
To put it completely bluntly, it was a few NV diehards who would take every possible opportunity to post 'gotchas' in AMD threads presenting the most favourable NV data and constantly attacking AMD's weaknesses like they are the only relevant workloads in computing. They didn't even care that much to post about NV, more about how AMD is bad, mkay.
They even took the chance to start new threads with extreme levels of pettiness and good old passive-aggressive snarkiness. The most obvious trait was basically blatant shilling of every single thing NV has done or is better at, and starting threads or jumping in threads with purely condescending comments. There are plenty of examples still around, and it hasn't fully stopped either.
The reverse happened rarely, every AMD thread eventually divulged into semantics with no reasonable discourse possible, so they pulled the plug. Especially with RDNA3 being an execution miss, that really ended any chance of rationality.
Until now, let us hope those responsible will leave well enough alone.
P.S. mentioned already ITT is that the final blame is on the moderator for allowing it to happen for a long time.