A couple of things about 'What ifs.'
The farther back in time one goes, the harder is is to say how subsequent events would have unfolded. The effect of a different outcome of WW1, for example, could have radically altered or prevented WW2.
True, fully agree. So we better fight about it today because tomorrow might be too late!

A significant change in a detail might only slightly change the course of history. Had Moscow fallen in 1941, Germany probably would still have lost the war. Hmm. I am disagreeing with myself. Let's see, Moscow falls, Germany gets nuked into the stone age, the Cold War doesn't happen ... maybe a huge change in history.
True. Germany did not have the population to hold all of Russia and her other conquests at the time. That has been verrified. (I have no source, I remember seeing a documentary a few years ago, but can't remember which).
'What if' can be fun, but it is not an exact science.
A group of historians are studying such. It is called Hypothetical History. A quote from the early days of this science can be found in the journal
The Economic History Review under the article
Hypothetical History by J.D. Gould. It states, "...recently some historians have urged that it is sometimes possible and convenient, or even necessary, to make counterfactual assumptions as a starting point for argument designed to assess the effect of historical events or processes." And here everyone thought I just liked playing "What if."

With regards to the opinion that Britain caused WW1, it is an over simplification. The causes of WW1 are many. Imperialism and industrialization are major factors. If Britain stepped in and somehow calmed Austria-Hungary in 1914, competition for colonies and resources would likely have provided another flashpoint. Impossible to say for sure. I will concede that Britain (and even Woodrow) had roles in the origins of the Great War, but they were not the only causes.
I agree, I might have over stepped my bounds in saying they were fully responsible because in that I have contradicted myself before. I believe they were a major point in WWI's beginning, more so than those we currently view in general terms as the parties responsible for it's start.