A couple of other things:
Kerbal is very nice about parts working. In real life, parts fail, fuel boils off after being stored for so long, electronics short out, rockets can only throttle so low, and hardware slowly decays from continuous exposure to solar UV and cosmic rays. It can be a very slow process, but it's a very there process.
Second, someone on reddit pointed out that in real life, Asparagus staging isn't really practical because the thrust to weight ratios of rockets and the wet-dry mass ratios of fuel tanks in real life are much higher, so there's more penalty for having dead weight in KSP, but more margin with part performance. In real life--parts can easily be destroyed by off-nominal launches, and don't have much margin for failure. Titan rockets couldn't even stand up under their own weight without being fueled up.