StrikeBack, I'm not talking about professional athletes here. I'm talking about regular guys who lift weights to get stronger and stay in shape, particularly guys who are not very young. I think that makes a large fraction of guys who read the forum.
These guys don't have the time or the expertise to follow protocols that are followed by professional powerlifters and the like. They also tend to spend a lot of their time sitting around in front of a screen (those who do not do manual labor, and even some of those who do). In the cold months, they are outside less, move around less and get less sun. When they're out they're exposed to colder temperatures. Their muscles and connective tissues are even tighter than usual. Then they go to the gym and lift excessively hard ("extra hard" like some guys have mentioned, because they lean on weightlifting to dispel their winter blues). Take all these things together, and you have a perfect recipe for a potentially serious injury.
What I'm suggesting is that guys like that take the realities into consideration and take extra care not to get injured in the cold seasons, and one way to do it is to vary your routine and use the winter for consolidation and reinforcement, rather than trying to go all out and risk injury. To me, "consolidation and reinforcement" still means working out harder than 95% of the dudes I see in the gym, so it's all relative.
I don't see why this is so difficult to understand. However, if you feel inspired to go harder than ever in the winter and can do so safely and effectively, then go for it. Every guy has to decide for himself what makes sense in his case.