I reckon there are some bike tourers who have not yet experienced riding in rain when they got miserably cold from not having rain gear or not enough rain gear, and then there are those who have and learn from it and do not have a big urge to repeat the experience.

I guess everyone needs to figure out what rain gear works for them personally and the riding/camping/temperature etc etc etc specifics , and go forward from there.

I'm completely in the camp of not fretting at all about the space and weight of carrying full rain gear, knowing I'm not going to get all chilled and miserable if the conditions go that way,--- and they can, and do, and will.