That's true, but they don't grit all roads and it's not every day that they drop grit.
A bit of a clean and a drop of oil should negate that.
I can't see why winter cycling would do more damage to a bike than summer cycling?
Whilst the salt washes off the roads fairly quickly, the grit element is pretty persistent and once they've gritted once, it's gritty for a good while. It doesn't just disappear at the end of the day.
I notice from another one of your posts that you're a mudguard user (like myself). Mudguards protect you and your bike from the worst of the grit. I have no idea how it works, but on my winter/wet bike, about 99% of the grit ends up on top of the rear mudguard and the rest of the bike stays surprisingly clean. I rarely clean it to be honest, and it looks pretty good.
Without mudguards on freshly gritted roads (pure misery), the bike looks like it has just been dug up off a beach.
Like a few others here, I've got a blue
Ribble for a winter/wet bike. I absolutely love it - it's a keeper.
Shimano 5800 and up callipers are very good and I have no problem stopping all 15st of me in wet weather when breaking from the drops. Earlier Shimano callipers are basically pointless in the rain imo - this might be the OP's problem.
I'm fine with 25mm tires, and I find there is plenty of clearance as long as the rear mudguard bracket binned and instead the guard is directly zip-tied to the brake bridge.