A rod which locks-up is essential....in certain situations.
Consider this;
You are sitting in a fighting chair attached to a 130lb IGFA big game outfit and your hooked into a fish which is 100m below the boat slugging it out like a pitbull.
If your rod just bends forever you will never be able to exert enough pressure on the fishes head to get it up and therefore swimming towards the surface.
In this situation your rod MUST lock-up.
It cannot keep on bending like a (cooked) stick of spaghetti.
A serious big game rod (one which has fought a number of big fish without failure) are made of E glass, rerely a carbon/glass or heaven forbid carbon
.
However, if you want to see rods truely locked-up please check-out the
Jigging Master website and you will see what a truely locked-up rod looks like........................but be prepared to be shocked, Jigging Masters engineering has world-wide aclaim because they are at the cutting edge of rod technology and also test their rods to destruction in real-life fishing situations videos evidence is on their site to prove it.
When I trot my float down the river I use a 6lb running line and a 4lb hook length/leader however I doubt I could break either line with my Hardy 13ft Specialist simpley because it seems to bend forever.......luuvely