Simulink is based on the block diagram notation used in control theory for decades earlier - before personal computers and workstations. The notation is rigorous enough you can pretty much pick up a book like the old Electro-Craft motor handbook (DC Motors Speed Controls Servo Systems), enter the diagrams into Simulink, and run them. With analogous allowances to how you would enter an old schematic into a SPICE simulator.

LabView was significantly more sui generis and originated on Macintosh about a decade earlier. I don't hate it but it really predates a lot of more recent user experience conventions.