1. On my Windows and Mac machines I refuse to install the Silverlight plug-in (I haven't found a site that legitimately needs it yet).
2. On my Ubuntu machine (where I generally read HN), there is no Silverlight plug-in (and Moonlight isn't advanced enough even if I wanted it). I'm not sure Chrome for Linux could deal with anything but the Flash plug-in yet anyway.
I refuse to install it because I haven't been convinced by people that I trust that there's anything that demands Silverlight. There's enough quality content that uses Flash that it's inescapable.
I'm not against installing Microsoft products on my system; I just upgraded the WMV codecs from Flip4Mac (now owned by Microsoft) last night. I've got Mac:Office. I'm just not interested in installing an inessential plug-in for something that I'm going to visit just once and probably never play with again.
You also didn't address the point that Silverlight just isn't cross-platform enough. Flash cross-platform support sucks (I can use it on Linux), but Silverlight cross-platform is nonexistent (as "Moonlight" is still essentially a Silverlight v1 implementation).
Not sure if the fail is on their side or yours.