*phew*
Thank you, Gordon...
I've resisted sharing my own feelings about this issue (every time I started to compose something, a little voice in the back of my head said, "nahhhh").
I'm nearly 50 years old, and have parked (and locked) plenty of bikes in my lifetime-to-date. Not to take potshots at anyone here, who thinks that the "Fahgettaboudit" lock is a good idea, but for me - it just ISN'T. It's like putting the most expensive lock you can find on the 3" thick solid oak door you install in your house... Anybody who really wants in isn't coming through the front door, anyways.
I stand back and look at my bike. In it's pre-electrified form, it was a 2004 Giant Sedona LX. In 2004 dollars, the pricetag was around $650 Canadian in the configuration I elected to purchase. Right now, the e-bike bits that have been added aside, the thing is a quick-release nighmare. I'm pretty sure that a casual passer-by is not going to free the hub motor from the frame wihout at least a 10" wrench, but...
Here's the thing - the bike, by virtue of what I (and most of you here) have done to it, is a rolling toy store. There are plenty of bits that are easily removable, if you elect to leave them attached and in plain view. My MR-11 based headlights just clip on to the handlebars. The rechargable battery pack that runs them has a quick-release that's attached to the head stock. My seat post (and the seat) are off the bike in a single wrist movement. My panniers and rear rack-pack have their own quick releases... And there's usually a Garmin GPS attached to the handlebars via it's own snap-in mechanism....
You see where I'm going - that my bike should include all of these goo-gahs is my own choice. If I don't trust the neighbourhood I'm in, I can't park it. And there's the rub... putting a chain through the wheels and frame just doesn't cover it, and unclipping all that shit and taking it with me... Nahhhh. Not a comfortable setup.
Going back to what Gordon said, though... A few years ago, I was sitting in a restaurant in Halifax, looking out the window and across the street. There was a big planter there, with a large arrangement of shrubs in it. A kid came around the corner on his bike (nothing weird about *that*) and stopped behind the planter. Then, much to my amazement, he pulled out a pair of bolt cutters that was down the back of this coat and underneath his backpack. The thing was longer than his upper body was tall. He tossed the tool (and a, now broken, SERIOUS chain into the bushes and rode off). Before I could consider calling this in - I honestly had NO idea what street I was on, let alone how to get ahold of the local police... This didn't seem worthy of 911 - he came back. On a different bike with a place to store the tool, and with his jacket and napsack collapsed in the rear carrier. He was also missing his baseball cap. Wouldn't have known it was the same guy, if I didn't see him pick up the cutters and stow them in carrier that ran along his top tube (looks like the kind of bag that you'd store photographic light stands in).
The point is, if someone wants your bike - and is "professional" about it - they'll get it. Carrying a ridiculously heavy chain around may give you a (false) sense of security, but to me - it just ain't worth the weight. Carrying a smaller and lighter cable lock (that's easier to handle and won't mar your frame) is just as sensible. Either will thwart the spontaneous casual theft of your bike... But a "pro" won't care WHAT the lock is made of...
Was it someone here who posted the link to a video made by some journalist down in the U.S. that set about parking his bike in numerous VERY visible places in a downtown setting and then "stealing" it (using the sort of enormous bolt cutters I described above) in broad daylight. Nobody interfered, and when he decided to feign difficulty with the cutters (to prolong the spectacle and interest more passers-by), one guy reasoned that the bike MUST belong the fake thief - why else would he be out in broad daylight with a pair of bolt cutters? After a quick exchange in which the journalist indicated that he'd lost his keys, the passer-by offered to HELP him...
My two cents. Everybody's mindset is different, but...