I think that the underlying desire in real name contributor policies is being able to define a chain of trust that this specific piece of meat is tied to this specific identity. Which I understand that desire. If you're trying to fight fraud and abuse, not to mention various legal liability and regulatory requirements, you want to have that identity to have a meaningful connection back to an actual specific oxygen consuming anxiety generator. The problem, as you point out, is that a "legal name" is not a catch all linkage between one feces producer and an identity. Oh sure, it works in many cases for people who are born and die with the same exact name, and aren't generally faced with harassment and abuse for that name being public information. That is traditionally ... cis men ... Which is the solution they've chosen to solve for.
Instead, there needs to be a more inclusive consideration of how to link an identity to a specific conglomeration of synapses - one that accepts that some people require pseudonyms, and that some peoples' identity relationship with governments can be complicated at best and adversarial at worst.