Couldn't possibly be the recording desk. Or the machines. Or the processing. Or the mics. Or the room design. Or the talent of the engineer. Or a dozen other variables
Sure there is a lot more to it - these studios cost millions. However you don't usually get overcompressed sound from artists that use ATC - the midrange clarity precludes this - distortion from overcompression becomes readily audible in the production stages. Think Pink Floyd, Mark Knopfler, Tom Petty, INXS and many others - kind of the antithesis of the hypercompressed Metallica sound. ATC is like having a "lens" on the midrange - forward sounding and too harsh for some but it tends to result in better recordings. This may seem like a shameless ATC plug - but there are grains of truth in these statements!