While most alternate history scenarios involve the people of a given era making different decisions that alter history. However, there are several scenarios out there that involve someone from the future travelling back in time, intentionally or unintentionally altering history in the process. The most infamous case of this is the book "Custer at the Alamo" (pictured below) in which Chief Sitting Bull casts a spell on Gen. Custer just before the Battle of Little Big Horn that sends Custer and some of his men through time and space to the Battle of the Alamo. This leads to the Texans successfully defending the Alamo, and Custer taking it upon himself to alter history to stop the US Civil War before it starts. A more beloved example of this would be the book "The Guns of the South" (also pictured below)

in which apartheid South Africans travel back in time to 1864 and arms the Confederate Army of Northern Virginia with AK-47s. What's your opinion of time travel in alternate history? Is it just a lazy copout that avoids the work of planning out a realistic scenario? Does it have some merit to show what radically different events could've played out if people had access to more knowledge and technology? Or is it just harmless fun? I look forward to hearing your answers.