To be honest, I don't know for sure.

Throughout the past century, engines have been running and living with carbon built up.
Small carbon particles filled up all machining grooves, and kept some lubricant in there to help in bad times.
Being an old farth, I know these engines ran very well indeed, though cleaning every now and then was required.
During these cleanups, one had a chance to check on the piston, ring and cylinder, and cylinderwear near the top of the stroke was quite pronounced.

Some of the new synthetic racing oils that exceed JASO TC class, leave the engine spotlessly clean after hours and hours of running. This is needed for the variable exhaust timing valves in competition engines, that would otherwise stick, and fail to function, being choked with carbon. The spinoff is a clean engine throughout, or a little bit very soft carbon build. The oil has lots of detergents and high pressure additives that seems to avoid or even prevent film breakdown by high ring pressures and roller bearing scuffing. On checkup time, less wear is visible, especially near the top of the stroke, and needle bearing running surfaces show a light tan (patina), without measurable wear.
Looking at all that clean bare metal inside, I sort of miss the thin carbon layer, that gave me so much proof of a well run engine. With the new oils, even guessing how long the engine has been run is a tricky task.

If a little soft carbon will worsen this condition?? Peronally I don't think so, though like stated, I am not sure.