One example would be state disability programs, they already need my real name and identity to work with me. Are there any downsides to sharing a simplelogin alias containing my real name vs no containing my real name? I just think it would be easier record keeping for them.
It’s better to use a custom domain or no alias at all for important personal stuff, but if your goal isn’t to be unidentifiable by the organization, then you can safely use your own name in the adresses. You will still have the advantage of spam control.
One downside I can think of is that the (government) organization will know that you use a particular aliasing service, which may be problematic in some situations.