MATLAB has divides graphics calls into "high level" and "low level".
"High level" calls check whether hold is on, and if not then they erase the current axes before adding the graphics.
"low level" calls never check hold, and always go ahead and add the graphics.
There are some functions such text() that are always low level. line() is low level, but plot() is high level.
There are some graphics calls that are high level or low level depending on how you call them.
When you call isosurface() without any outputs then it calls patch() to draw the surface. It does that with a calling sequence that happens to be low level for patch. So when you call isosurface that way, the surface is just added to the current graphics, and higher level graphics functions are not invoked. In particular, view(3) is not automatically called by patch() the way it might be if a high level calling sequence had been used.
