Balancer slides in on install

It is an interesting question and I don't know the answer. Some OEM engineers didn't think a press fit was a requirement, others did. A lot of Ford engines used a slip fit damper. It all worked okay for passenger car use. For a low budget rebuild on a passenger car engine I wouldn't be afraid of a slip fit. I'd rather not have a slip fit, but if it was my only option I'd take it.
For racing the recommendation is always use a slight press fit. Somewhere in the 0.0005 to 0.001 range depending on the size of the crank snout.