Except that "lifting weights" doesn't just mean what you think it means. You might be surprised if you were to look at the breadth of what is strength training today, rather than superficial impressions of it. You seem to believe that all "lifting weights" takes place in racks that limit the range of motion and isolate the work to one individual muscle group. That's just not so. Many strength training regimens are specifically designed around a goal of functional strength, not bulking up isolated muscle groups.
Sure, but you notice that the OP began with a very general statement - thus the general replies. Are there strength training regimens that are good for IP? Sure - but generally speaking, what most people do when they talk about weight lifting aren't it.