There are other blokes who mindfucked the world and penned down some of their ideas who similarly, and maybe for similar reasons did not make the list. There's Mao Tse-Tung's 'Quotations from Chairman Mao Tse-tung' and other works published in his name [1], countless works 'by' Joseph Stalin [2], Adolf Hitler's 'Mein Kampf' and other works in his name [3] just to mention a few. All of these had great impact on the world and inspired countless people just like the collected works of Karl Marx and Friedrich Engels. I suspect this is not the type of inspiration the authors of the list are looking for, hence their omission.

[1] https://www.goodreads.com/author/show/4797485.Mao_Zedong

[2] https://www.goodreads.com/author/list/138332.Joseph_Stalin

[3] https://www.goodreads.com/author/show/30691.Adolf_Hitler