>>96398583
>a Back carriage carrying combustible fuel
It's better than having all that fuel inside of the tank, where any good hit will just turn the whole thing into a torch. If the trailer gets hit and the fuel blows up, the tanks will be unaffected and can continue as is.
>>96398697
Churchill was well armoured and the flamethrower variant kept the main gun, allowing it to fire both 75mm shells and fire.
>>96398739
>same reason the Stuka or other designs
Flamethrower tanks were constructed well into the 60s. We just invented other ways of projecting fire to make them obsolete. Dive bombers were made obsolete by improved air-defences, guided bombs and jet fighters able to make similar strikes without having the entire plane built around one concept.
>One mortar and it was over.
How so? For one, it's not easy to hit a tank with a mortar or even artillery, unless it's guided. Even if you destroy the trailer, all you did was deplete fuel for the flamethrower. The Churchill still had a normal tank gun on the turret.