A couple of examples:

- My ultralight packs (e.g. a GoLite Speed, a custom Pulag pack); these weigh under 2 lb, are made of very lightweight material, and are meant to carry under 30 lb (better under 20 lb). They're great for fast backpacking on good trails in California weather...not good for loading up with lots of gear, tossing in a trunk or cargo hold, moving through thick brush, weathering a huge storm.
- Alcohol and canister stoves: great for lightweight backpacking, not so great for survival (scarcity of fuel, inconvenience, etc.)
- Lightweight trail runners - again, great for hiking with a light pack, not so good for extended wear or protecting feet in wide-ranging conditions
- Ultralight down sleeping bags - my Montbell bag in particular (18 oz) would be inadequate and too fragile for a survival kit, though it's great for ultralight backpacking
- Lightweight DWR top - great for fast hiking in specific climates, good against wind, light precipitation; would fall apart quickly in a survival situation and won't protect against enough conditions
- I could go on and on...

Again, I suppose one could find a place for any of these in a specific, tailored kit - I just am more selective about what goes in my survival kit versus what I'd take for a backpacking trip in an area where I'm comfortable and experienced, like the central Sierra Nevada or California Coast. I also know how to maximize this gear for the kind of survival situation I might get into if I somehow got off trail or injured (balanced versus carry weight and increased chance of injury as I load up), versus the gear I'd like to have in my BOB or car (carry weight less important).

So, there's other equipment I no longer use for backpacking because it's just too heavy, such as an Arc'teryx Bora pack, that would be fine for a long-term survival situation.

I'm really comfortable with minimalist backpacking, so that is also a factor in this - people with more old-school gear will find that it probably crosses over better for survival, though there's nothing wrong with looking at how to minimize weight and multiply functionality for our BOBs and survival kits. I bet most of us here think about that.