Whilst mostly agreeing with you Sam, especially your sentiments, I'd add that its easier (and maybe more 'forgiveable') to get snapped by a fish getting into a snag than to be snapped in open water. When the latter happens, the angler is almost always and almost entirely to blame.. e.g. his reel clutch is no good or set incorrectly, he's using unbalanced tackle, line is damaged etc.
Yes, 100lb+ shark can and are landed on 10lb bs line.. but in open water.
But that shark, when eventually landed, will be TOTALLY knackered... as will any barbel over 5lbs be when eventually landed on, say, 5lb bs line + 1.25tc rod.
Steven.. my view would be, match your rod to the line strength you're using. And if you fish within 20yds of any snag, don't use less than 10bs line. In my experience, if your using 12bs, then a 1.75-2.2tc is fine.
I mainly fish the Teme..a river full of snags (and snags is where the barbel reside in summer during daylight). I started this season using 1.75tc after using 2.2tc through the winter.. and found I was frighteningly undergunned, almost losing 2 good fish in snags first session out.
I'd feel totally confident fishing with an Avon rod for double-figure carp in a snag-free stillwater.. but I'd feel irresponsible using the same rod to fish for barbel in a snaggy river.
There is nothing worse than being connected to a good barbel, with your rod wrapped round to its grunting max and your line 'singing'.. and knowing that you are not in control.
I give respect to all other angler's views.. but my greatest respect goes to the barbel I'm fishing for.