Bitcoin was initially designed with a fully fleshed out scripting language, intended to encompass and support any potential safe use case that users could come up with in the future. As Satoshi himself put it before he disappeared:

“The nature of Bitcoin is such that once version 0.1 was released, the core design was set in stone for the rest of its lifetime. Because of that, I wanted to design it to support every possible transaction type I could think of. The problem was, each thing required special support code and data fields whether it was used or not, and only covered one special case at a time. It would have been an explosion of special cases. The solution was script, which…

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