> Even rewrites that have a decade old code base to be inspired from, often fail due to the sheer amount of things to consider.
The amount of knowledge required to first generate the codebase, that is now missing for the rewrite, is the elephant in the room for rewrites. That's a decade of decision making, business rules changing, knowledge leaving when people depart etc.
Much like your example, if you think all the information is in the codebase then you should go away and start talking to the business stakeholders until you understand the scope of what you don't currently know.
The amount of knowledge required to first generate the codebase, that is now missing for the rewrite, is the elephant in the room for rewrites. That's a decade of decision making, business rules changing, knowledge leaving when people depart etc.
Much like your example, if you think all the information is in the codebase then you should go away and start talking to the business stakeholders until you understand the scope of what you don't currently know.