The government would need to know what to subpoena, and what to prioritize as well. In principle could the government subpoena my ISP, learn I'd used a VPN, subpoena the VPN, learned I visited Wikipedia, then subpoena Wikipedia to finally learn what articles I'd written. Yes, but in practice this will never happen. There's no interest in doing so, and it's unclear a judge would be convinced that useful information could be obtained from such a path.

On the other hand, if I'm making death threats on Facebook, there's a much more realistic path: view the threats from a public source --> subpoena Facebook for private data.

Treating the two risks as similar is madness.