I'm not sure why the downvotes. That seems to be a statement of fact.
You can do a certain amount of identity obfuscation online but for anyone with a real professional profile you're generally not really anonymous if anyone really cares to find out your true name.
Me neither, i even provided a source, and it's easy to find other examples. There certainly are projects that allow anonymous contributions, but i doubt it's the majority of projects that one would consider important.
For these kinds of projects you could make up an identity relatively easily and nobody would know, but you're screwing over the project (as they may need to remove your contributions if they find out), so it's not something to be doing if you actually want to contribute (instead of inserting backdoors).
The original idea (not being able to contribute without a verified identity) is still wrong, but it's wrong because it's impractical to prove identity in a way that people find acceptable (and works), not because people will not give up anonymity, as many of the replies state.
There are people who downvote things that present facts that aren't in accordance with how they think the world should be.
I do think it's difficult to verify identity in any reasonably acceptable lightweight way. That said, for the larger projects I'm most familiar with, a lot of people work for companies, attend conferences, etc. They may go by nicknames day to day, but they have known real identities and their professional existence wouldn't be possible without one.
You can do a certain amount of identity obfuscation online but for anyone with a real professional profile you're generally not really anonymous if anyone really cares to find out your true name.