Thanks for this callout. That webpage has a great white paper (non peer reviewed):
It has some bias (because they are selling the service) and not enough samples IMO, but it still has some great insight. The TLDR is that the smoothed surfaces can double the fatigue life:
Totally worth a read if you are poking around in 3D-printed parts. Here it is in PDF form to preserve the research:
Surface Treatment of Powder-Bed Fusion Additive Manufactured Metals for Improved Fatigue Life - REM Surface Engineering.pdf (1.6 MB)