'rigorous' comes from a Latin word meaning stiff or rigid. C.f. inflexible.
Sure, but it also has a connotation of being hard-working, focused, and diligent. As centuries go on, sometimes words take on slightly different meanings in addition to their original meaning. The INTJ's I know are rigorous, but I think of it in an admirable way. Sometimes in the way you mention also, but I do admire the rigor with which they go about their business day in and day out.
NTJ's are the only types that have ever made me feel emo.
ENP's are the only types that have ever made me feel like a sensor.
There are two great days in a person's life - the day we are born and the day we discover why. --William Barclay