interesting. Was your old bicycle steel or perhaps aluminum? Most of mine are vintage steel and would rather not risk the rust, but a beater aluminum bike would be less worry.
The road bike I spoke of was a Columbus tubed steel bike, built with Campy Record in the late sixties. Like many of my friends of that era, I suffered a frozen post due to galvanic corrosion, but no other consequences attributable to rain. It saw little maintenance, partly owing to grease fittings I installed on the hubs, and an adaptor that allowed me to grease the pedals via the dust cap. So, the only effort needed was my annual (post winter) teardown of the BB and headset.
The original chrome, like most Italian bikes of the era was crappy, so when the time came, I stripped the frame and had it chromed to military specs by a firm that did submarine parts for the USN. The the friend who was painting it suggested that marine hull paint would be appropriate given that it spent so much time wet.
It's been my experience over the last 50 years that riding a bike in the rain is pretty harmless. Much worse is storing a bike in a damp environment for the long term.
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Lest you ask, the commuter I ride now is lugged and bonded aluminum, and it's holding up fine. Knowing I didn't want to worry about it, I built it with SunTour Grease Guard, so there's no annual teardown, and in about 25,000 all weather miles the only parts replaced were worn chains and freewheel (once so far), a few rear axles which snappped, and one rear hub bearing which actually wore out (though I suspect it was related to riding with a broken axle).
I don't think I'm unique, except perhaps in the amount of rain miles (and the submersions), and suspect that many old timers had similar luck with their primitive hardware.