Because it's easier to have it so players can just click the version text in the game menu and open the update log from a local .rtf file due to the way i develop the game.
Well the game isn't just downloaded from itch.io, it's also uploaded to a few other places, I'd have to upload the update log to every description on every site and most of them have a character limit that aint that long. So just having a way to open a text file with the log from the game menu was easier and negated the whole description character limit of other sites the game is uploaded to, so was more a habit of convenience, :o