Let me clarify. Consider if I instead chose equal and not equal as my operators. Now a "small change" probably won't even be a valid program (not wqual). Any small change that does result in a valid program is unlikely to result in an equally small behavior change for any interesting input. Changing a strictly-less-than to a less-than-or-equal-to is a small change that results in what seems like a small behavior change when viewed locally. But my own experience with programming is that a local change such as that will have huge consequences later on - often to the point that the program crashes.
Consider it this way: the space of valid programs is infinite. The space of valid programs that solve a particular problem is much smaller (in the physics << sense) than the space of valid programs. Any perturbation from a valid program that solves the problem is much more likely (>>) to land you on a valid program that does not solve your problem than one that does.