Flow can be considerably slower when changes involving such older technology are required, either because more manual tests must be run or difficulties are expecting implementing changes due to poor documentation and lack of an open, supportive community of users (a given for modern tech stacks). Finally, the ecosystem of tools (IDEs, build tools, testing tools, etc.) around such technology tends to behave and feel very different from modern ecosystems, increasing the cognitive load on team members that need to switch between these very different technologies.
