All wikipedia content requires a valid citation.  There is no validity in the 'common sense' claim because things don't always follow common sense.  All of the tubes listed in the paragraph claiming low output were specifically designed to give rasonable output at low voltages.  One, the 35L6 is capable of managing 1.5 watts with a plate voltage of just 35 volts when the bias is properly adjusted.  Oddly, and because of the tetrode characteristics, it actually rises to 2.5 watts at 25 volts.  You cannot claim that is significantly lower than it maximum rated output of 3 watts.  None of the tubes listed will turn in less than 1.5 watts at 32 volts. Article ammended accordingly.