I am just lost for words when I read some of these posts, but than again what do I know, I just been flying since 1990. I flew loads in Scandinavia too in SEP. The day I took my PPL, me and another student spent 4 - 5 hours de-icing the airplane before we could fly to make our test.
I wonder why airlines operate with clean aircraft concept? And if ice accretion expected you need to add XX amounts of knots on your approach speeds etc. Equally if heavy rain, as the aerodynamic surfaces will change their behaviour.
Than again I am not one of those who loads up a C172 full with fuel, 4 pax and takes off without checking their weight and balance, and just about scrubs over the top of the trees during take off.
Taking those "chances", is the reason people get into trouble every year, because they don't respect the forecast, weather, and fly into conditions they are not qualified to fly in, don't have the right equipment to fly in.
I am instrument rated, but still I would not fly into a cloud with C172 as it does not have the right equipment to protect against ice, if flying in icing conditions.
Anybody believing you can't pick up ice from rain is living in La La land.