Do you think reading challenges are silly? I read a decent amount of books this year however the arbitrary challenge I set myself hasn't been met </3

try not to think about it
Nothing is silly if it shapes what you do for the better. May be more comfortable to have a reading goal to walk towards rather than a challenge you have to sprint for though.
They're silly but there's nothing wrong with that.
What is a semester's curriculum but a reading challenge with extra bits? And absolutely nobody has ever thought school is silly.
They are arbitrary but ultimately they push you to read more so I think the ends justify the means. As long as it doesn't mean reading lower quality books then you would otherwise just to finish the challenge.
I suppose the real question is "is reading more an inherent good?" to which I don't think the answer is obviously yes, even if you're only reading the 'good' stuff. If we were to imagine the purpose of reading is to enhance understanding, for instance, reading too much has a high chance to muddle things.
Definitely you are right, the more = better mentality isn't always correct. Nevertheless I think for many people in the modern world a reading challenge isn't going to be the difference between 10 or 11 hours a day; rather it might be between reading 30min or not reading at all. So in general I think it should be promoted.
To me, it's not silly. Make it your tool. I don't subscribe to it on a regular basis, but if you want to say read more Vs scroll more on a specific timeframe and would like a tool to keep track then why not? Just don't stress about it.