Well, we need to make a decision about when to guess, and so we opt to only do that when it’s an educated guess. If your point is that we won’t be blamed for guessing incorrectly… we will have to disagree on that 
The Bill Evans example I mentioned here is a good one to keep in mind. As soon as something in your collection matches our metadata, we assume that unidentified Sheryl Crow is the same person as the one in our metadata model. Just remember that in lots of cases it’s less clear – our system tracks two different Nancy Wilsons, two different Steve Wilsons, 5 different people for both Steve Davis and “Moss”, 6 different people for “Nicole”, and so on.
This stuff can get messy even when we’re relatively conservative about guessing, so this is the current designed behavior. Just remember that nothing is preventing you from clicking “Create Artist” to create a new performer in your library. This is about when that performer is linked to someone in our database.
Sheryl Crow seems like an obvious example but we need to consider the full spectrum of cases, and the current behavior is designed to prevent errors that can arise when we take an unknown person and link them to our data without sufficient confidence.
Like many metadata issues in Roon, my advice would be to spend your time matching your content to our model when possible (which will sidestep these issues and automatically link content to the appropriate people), as opposed to manually entering data by hand.