Why would more of any component be presumed to sound better?
Its possible for anything to be too simple to do its job. For example, if there is only a single tube in a line section, you might have a fairly high output impedance, which will be exacerbated by the output coupling capacitor (even higher output impedance at bass frequencies). This can have a big effect on your results in particular if you want to drive a particular solid state power amp or if you need to drive a longer interconnect cable.