The concept of wanking on Alternate history has always existed in Alternate history and is often wishful thinking on the part of the Author for plot reasons or personal preferences.
It of course is insufferable in so many cases seeing a nation rise to near absolute supremacy with little effort and no consequences and establishes an eternal hegemony that will never die. Something that must be realised is that no matter now powerful or enormous a nation may become it will die. Every super Empire like the Romans, Germans or British believed. However even modern powers believe this and one day the United States of America, Russian Federation and People's Republic of china will all wither and die one day like Rome, Mongolia and Britain did.
However a wanked nation is not impossible. The Alexandrian Empire rose from a small backward state to the largest Empire yet existed in just 7-8 years. Genghis Khan created an Empire that stretched from Persia to Korea in around a decade and the British Empire took over a quarter of the planet in under a century. However whilst they did this they didn't last forever despite their power and determination to survive.