Well, I think a poor-man screen saver was a common enough use case for that. That said, you can (or, rather, could) control the images. There's a flag in GIF8

Well, I think a poor-man screen saver was a common enough use case for that. That said, you can (or, rather, could) control the images. There's a flag in GIF89a that allows the viewer to skip ahead to the next frame on user input. No modern GIF viewer supports this anymore either. BOB_89A.GIF used this feature to let you skip ahead if you didn't want to just passively watch the slide show.