before and after apache logs showing much less crap in them from bots. Do you think the maintainers of https://lore.kernel.org/ would leave something in that didn't work? It isn't perfect but I have run it on a (much smaller) web site getting hammered by bots and logged "before" and "after" and the difference is measurable.
Its literally trivially objectively measurable, this isn't something that is based in opinion.
You can throw it up on your own website and simply grep the logs if you don't trust it, or look for the analysis reports from people who have done exactly that.
Like the other commenter said, why would linux.org deploy and leave deployed a technology that did nothing? Do they just enjoy trolling users? I doubt it.