There are some edge cases that it would impact. But, yes, it's pretty rare and USCIS estimates it would only impact about 25 cases a year. I don't think their estimate is off-base. I have a lot of experience with the US immigration system and I'm familiar with many major components of it, and I pay close attention to any major policy changes that occur. This is a perplexing shift in policy because it doesn't make a whole lot of logical sense.
The previous policy didn't seem to be creating any issues -- particularly because very few people needed to obtain citizenship through the alternate method. That's why it's odd that this administration decided to make any change to it. There doesn't seem to be any benefit to the country in doing so, and the only potential impact is to make things much tougher (or impossible) for a handful of people.
So why make the change and dedicate resources to doing so? That's the million dollar question here. And given this administration's history with immigration policy -- especially Stephen Miller's attempts at backdooring significant changes to the immigration system through administrative changes and EOs -- one has to wonder if this change is the prelude to something else. And I think that's especially true considering this policy change has occurred alongside major recent changes in the top leadership of USCIS, ICE, CBP, and other agencies responsible for enforcing or administering our immigration laws.
I'm not a conspiracy theorist -- I think anyone who's read my posts would agree -- but people generally don't do things just to do them. There has been a pretty consistent laying of groundwork for major changes to our immigration system through EOs, policy changes, and this admin's handling of federal court cases pertaining to immigration law and policy.
It hasn't been an abrupt shift, but rather a slow and consistent approach of making changes that substantially reduce the avenues available for legal immigration, and changes that make the financial and evidentiary burden much higher for people who are eligible for things like permanent residency and citizenship. This administration says their focus is on illegal immigration, but the vast majority of their actions have taken place in areas that correspond almost exclusively to legal immigration. It's not as if Stephen Miller has been shy about his desire to reduce legal immigration to a small fraction of the annual amounts this country has averaged for decades, and such changes comport with this admin's strategy of making major policy and regulatory changes via Executive branch action in lieu of the usual legislative process.