I sometimes come upon customers that have specific requirements but which has elements which closely match that of something else.
I do often think well why start from scratch. Why not start from a base, like using a CRM, and then customise, or add on modules to support all the new functionality.
Its like building a new car by taking apart a current car and welding on a new one on top. Nobody wants to weld together a new frame with all the issues that go along with that. Nobody wants to build a complete new wiring loop.
Some software is the same, start with a basic building block and take out what you don’t need, change what base parts you do (aka modify the frame) and then add on what you do (weld on new body panels).
This does sound simple enough in the software and open-source business.
Until you look at the licencing!