If you increase the difficulty much beyond what it currently is, legitimate users end up having to wait for ages.

And if you don't increase it, crawlers will DoS the sites again and legitimate users will have to wait until the next tech hype bubble for the site to load, which is the reason why software like Anubis is being installed in the first place.

	▲	shkkmo 6 days ago \| parent [-]
		If you triple the difficulty, the cost of solving the PoW is still neglible to the crawlers but you've harmed real users even more. The reason why anubis works is not the PoW, it is that the dev time to implement the bypass takes out the lowest effort bots. Thus the correct response is to keep the PoW difficulty low so you minimize harm to real users. Or better yet, implementing your own custom check that doesn't use any PoW and relies on ever higher obscurity to block the low effort bots. The more anubis is used, the less effective it is and the more it harms real users.