The threat of developer and user drain is real. Forks can be good if a project is 'dead' or devs want to push it in a significantly different direction. But two

The threat of developer and user drain is real. Forks can be good if a project is 'dead' or devs want to push it in a significantly different direction. But two forks that are similar and competing create subtle incompatibilities that force a developer to waste time doing something twice or, worse, add a feature/patch to only one branch and not the other. I would find it difficult to claim that code could flow "fluidily" between two forks -- forks are by definition different codebases and will always require extra work to cross-develop for.