See their post here: I find it a bit unusual that they decided to ban cards that were so popular and have been around for so long, but they offer a pretty good explanation in the article: its experimental
Some of these cards were obviously powerful, but others just looked like regular MTG cards
This card was originally expected only to given away with the English language release, but Ichikawa personally advocated for a Japanese version to ensure it reached Japanese players
Beast Within Beast Within is another anything-goes removal spell that gets reprinted often
For example, Gust Walker, Khenra Scrapper, Glorybringer, and Combat Celebrant, among more, would all be nice to slap free Kaldra Completant and Colososus Hammer's onto
This little guy can basically stack a pile of cards on top of your library thatll win the game on the spot