I'm not sure I'd go that far with the optimism, at least in my field (artificial intelligence). Some obviously bad work does immediately fade into obscurity, and better work probably does on average get more attention, but the variation is huge. There is so much stuff on arXiv, that to get attention you need some kind of PR push so people notice it in the firehose, or a dice-roll around a viral tweet or science journalist noticing it. Some of the better funded university and corporate research groups have actual professional PR and science-comm teams doing coordinated social-media blitzes, press releases, and blog posts around new arXiv papers! That's a huge factor in determining whether a given paper gets attention.