it's not really that Google lags, but rather SEOers have optimized for Google. The problem is intractable. When people talk about the 'good ol days' or times when Google was better, it was simply because there was less SEO, less spam and generally fewer pages on the internet.

Google could be better than it is now, but there's no incentive to do so, unfortunately. Say Google allowed you to blacklist entire sites from the results - inevitably those sites that have the most ads would be the most likely to be blocked, resulting in lower revenue for Google.