I highly doubt Netflix DVDs were a high source of P2P rips. By the time something's available on DVD, it's already been ripped by scene groups from pre-release sources.
If anything, DVD ripping probably helped Netflix, as subscribers used it to build their own private archives.
Is this true? A friend tells me that torrents for new episodes of ongoing stream-only shows are typically up within minutes to hours of being released.
Both are true. There is more significant DRM on most streaming services than DVD, but also pirates are still consistently beating it. Hard to say if that had much of an impact on this decision though.
Netflix DRM playback is harder to deal with.