as a person who spent years building flow.ai before flowise.ai, i'd say drag n drop ui was dead on arrival it works for a set of very hand picked cusomers , the rest were in a weird spot between people who can code( and think accordingly ) and don't.
I do still use a part of it on one of my projects for building multi-step image processing pipelines for AI property photo editing (ffocal.io for the curious) that are configurable in the admin panel and it works super well and is useful for modifying and testing pipelines. So there are use cases, they're just very narrow