Probably some do, some don't. It really depends on the recording conditions. I was watching the Production Voices guy talk about the recording environment for the 300 Grand the other day, and if you can control the background noise floor and external impulses in a studio, then the post production is not necessary.
But for me, I record in people's homes, and it's far from silent, even when I ask the resident, who is usually a friend, to be as silent as possible. Most people don't appreciate what silence really is. I've had to time my recordings between traffic lights down the street because cars would drive by (coming from Apple HQ) as notes were recorded. I try to scope out homes before setup because gardeners make an impressive amount of noise outside, and birds in morning can really ruin things. I've found that re-recording and patience save more time than having to use the audio tools in post generally.
Anyways, I spend alot of time in post processing - first removing the background noise floor, which can have refrigerators and other hums in the house. Then, I go through and remove birds, lawnmowers, pots and pans, alarms, phone noises, airplanes by hand - yes it's painstaking. But I feel I've found the balance between a quality instrument and too much time spent removing noises. Part of it is not recording 88 keys, as I only record minor thirds up the KB. The bad part of this is that chromatic scales can sound funny if you repeatedly play the same sample over and over again pitched up/down. But I only have to deal with less than 30 notes per velocity layer, and removing birds from 88 note recordings per velocity layer x 16 layers x 12 microphones would take extreme (more extreme than my) patience and commitment. I'm committed, but I have my limits. Editing is fun to some extent as the tools nowadays are amazing - you don't need a recording studio - just time and commitment.
