[ChuckMcM]

Because they very much have to toe the line of being "neutral" in their search results as to not enable all the sanctions/remedies that other search engine competitors (like Bing) to have merit. Were they to overtly use their position to "punish" the content companies in this way, they would be jumped on by regulators everywhere for abusing a monopoly power.

[venomsnake]

Torrent sites downgrade, as searching for torrents were exactly that. Punishing arbitrary sites for no good reason.

[Spivak]

The sad reality is that torrent sites don't have large legal teams nor the public favor to win over judges and juries. In the mind of the public and lawmakers, they are punishing the "bad people". Any search provider will be able to continue this practice with impunity as long as they don't target people with real money.