"Competence Debt: ... The gap between what is in your codebase and how much of it you understand..."

Over the years I have worked on a number of replacement projects. Looking back I realize that the real motive for many of these replacements was a severe competence debt in the old system. People would claim that the old system was impossible to maintain when the real problem was that they did not understand how it worked. Yes, technical debt made things worse since the confusing code and lack of automated tests made it frustrating to understand the system.
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Unfortunately, replacing a system just because the competence debt in the old one is too high is seldom a good idea. The whole project lacks meaning for the users since the new system will not give them any visible improvements.
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Ironically, the process of replacing a system often forces developers to study the old system, thereby reducing competence debt in it…
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