From a logical time-divergence point of view, my only issue with the stunted technology growth is that even if those key figures in Europe might have died, others not just in Europe but the rest of the world would have risen to take their place. Most technological innovations were made by various people independently, and then only after it became important people would figure out who did it first. Not to mention North America with practically equal technology and South America/Australia only a bit behind that of Europe, which suffered no such destruction. Admittedly many nations don't have a lot of scientists/are fairly undeveloped (like my own), but Canada, America, and Australia would have been the primary nations pushing things along, and even a lack of economic development doesn't mean a lack of technological progress.

Just my two cents on the subject.