Factorio started in 2013. Satisfactory started development in 2016 and released 2019. At the time Satisfactory was released it seemed already more advanced than Factorio -- and after only having been developed for half as long. (The visual complexity of Coffee Stain's game is off the charts compared to Factorio. Factorio has a board game style whereas Satisfactory is a modern 3D game. Look at the launch trailers.)
Coffee Stain has about 25 employees working on 2 games (Goat Simulator and Satisfactory), Wube Software has 15 employees working on 1 game (Factorio).
Having read Factorio's dev blogs I feel like there might have been a bit of not invented here syndrome. They wrote their own UI toolkit for instance. Maybe they kept inventing technologies while Coffee Stain found ways to reuse existing tools?