From the introduction:
As the name implies, Streamlined Modern Adventures & Combat is intended to be a system in which gameplay flows smoothly. Players shouldn’t need to constantly be performing math in their head on every roll, and Game Masters should have a minimum number of charts and tables to consult. This of course is an objectively superior experience.
This system is a direct response to games like Pathfinder 2nd Edition where every roll involves large, uneven modifiers that slow the gameplay down as players have to perform addition and subtraction in their heads to decipher the true results of their roll. It is also an answer against games such as those in Modiphius’ 2d20 System, or the World of Darkness/Chronicles of Darkness product line where I believe too much is abstracted. A balance is sought between simulation and abstraction, and the focus is on keeping the rolling and roleplaying flowing.