Because French/ British naval guns would prove to be the perfect solution to German defenses, despite high velocity long range guns being the opposite profile to typical siege artillery
With a PoD of 1 August 1914 at the start of some sort of WW1: if the situation demanded it, how quickly could the French and British come up with a siege train similar to that of the Germans in 1914?
I wouldn't expect guns to be the equal of the peacetime-designed, well thought out big Bertha and Skoda howitzers, but rather what could be improvised on short order and when could it be available?