Another follow-up. One of the threads about this issue has 222 replies and 13K views in just 3 days. They fixed the email sending blank account names for me (apparently, some people still get a blank account name) but when I try to login it still tells me the account does not exist.
I'm a software developer and I'm always working on huge databases (both in terms of records and entities/relations) and I know maintenance and migrations are somewhat of a russian roulette but I'm trying to figure out how they can tell me my account name through email at the same time both the client and the website tell me that my account does not exist. The only explanation that makes sense is a propagation issue since Steam must have many systems holding their IS. Well, that or some systems analyst figuring that it would be a good idea to have redundant login entities without referential integrity... but that's just too horrible a scenario to contemplate.