My experience has been with Diehl saws, and when they are maintained, they are wonderful machines, capable of running 24 hrs a day for....years.
A Ripsaw is considered a rough mill machine, and is often the first machine the lumber meets after the kiln. It is used for breaking down the boards into sizes for all subsequent operations. We used ours to make molding blanks by the thousands, as well as rip onesies and twosies for custom work.
The ripsaw would produce a glue line quality joint on lumber - even rough boards. We would glue up 1x12 directly off the saw nearly every day. It required a machine properly maintained and set up, as well as a saw blade that was sharpened for that type of work.
One edge of the rough boards would be straightened using either the old Carter shadow line from above, or the newer laser lines. This line had to align properly with the projected cut and the saw blade. Then that straight and clean edge would be placed against the short fence and ripped to the width needed. The operator had to have some experience and skill to get consistent results.
If we wanted maximum width from the boards, the fence was pushed aside, and the whole board could be ripped on one edge, then the other. Knots or other defects could also be removed.
If the oilers were not adjusted correctly on our saws, some oil might show up on the lumber, but would be milled off in subsequent operations. The Diehl machines had lower tracks with triangular teeth that could leave dents in pine. It is not considered a finish machine, with the exception of that nice glue line.