I wouldn't entirely agree. If you aren't lifting any relatively heavy, extra weights, e.g. running or something, warming up isn't as important. However, when lifting relatively heavy weights, I think warming up is pretty important.

Warming up has the benefit of lubing up your joints. I think we've all had the instance where our body are relatively stiff and if we do, say, a push up, our joints pop or make cracking sounds. I remember squatting once when I didn't fully warm up. My knee wanted to pop during the squat and it felt extremely uncomfortable trying to exert force on that leg. When there isn't any extra weight, merely extending your leg with a pop wouldn't bother anybody, but exerting a lot of force and doing so slowly sure wasn't a pleasant experience. What are the chances of serious injury? I don't know, but it hurt enough for me to not want to find out.

Another thing warming up helps with is to acclimate you to your working set weight. I know the first set of my bench press usually ends in a grinder and is the roughest out of all my sets. I'm not sure if it's just my mind acclimating to the weight or a physiological thing like more blood getting pumped to my muscles. Either way, I'm fairly certain (but do not have any sources) injury rates would be increased if you tried to deadlift your max without properly warming up.