For those proficient in writing textual programs, a tool such as Flyde as-is might provide value by enforcing modules to be stand-alone and well-defined; the premise of https://en.wikipedia.org/wiki/Flow-based_programming as a paradigm that promised value even without using a visual editor, and just by adhering to the concept.
But for those who lack the understanding of coding syntax and grammar, a visual tool, even in a not-much-higher level of attraction, could make all the difference. I've personally mentored dozens of entry-level developers many struggled with concurrency and asynchronicity. (callbacks, promises, etc). these are concepts that become a no-brainer using a nodes-and-wires editor.
Regarding prepping - fair point. I'm sure it's not what you meant, but here's a grep in a Flyde flow (the second example) - https://imgur.com/a/V9u1ETl