It's not rubbish to say that flying with an instructor teaches you to deal with unexpected weather conditions. When you are driving a car, did your instructor teach you how to avoid aqua planing or tell you it's raining, therefore too dangerous - go home.
The fact is we live in the UK and unless you want to fly once every 8 weeks on the weekend in perfect sunshine, there may be rain that comes and goes, or in the winter rain/snow that blows through quickly. I would not plan a long distance flight in these conditions and don't have the experience to do so, but local with a risk of a shower? for sure, unless of course the forecast is for CBs etc. Icing is a whole other issue and not one to which my original post makes reference.
The point is you don't plan to fly through rain for an hour, but if you are up and it happens, you need to know how to deal with it in a calm and measured way. Learning to be a pilot is learning when not to go flying at all, but it is also dealing with challenging situations calmly when they arise - the pilot mentality. For me, this is learning from someone more experienced than myself not to "panic" in a rain shower, or if the clouds drop to 500ft. In the scary situation mentioned above where icing occurred, did the person learn from an instructor what to do if icing occurs? We learn from our instructor's experience so we don't make the same mistakes - even if what we learn is to stay on the ground that day!