Well there are two parts to this debate it seems. One is the trend by some to just ‘fake it’ without trying to really invest artistically into any esthetic role. The other is the debate whether Steampunk stops at a certain time or is an alternative history line that moves forward into modern times and beyond where steam rather then the internal combustion engine became dominant and electricity also is sublimated to steam, where Zeppelins and Dirigibles became a major form of transportation rather then being faded out, etc…
Along these lines it seems boilers being large and unwieldy for power sources means that the continuation of science along those lines would focus on getting the power of phase change into a smaller and more wieldy fashion which would mean a lot of research on gasses, pressure, thermodynamics etc… which would allow smaller devices for power units using perhaps something other then just water, i.e. the purpose behind green glowy stuff (like antifreeze) etc.. in Steampunk in some people’s artwork.
Steampunk Sci-fi could be an interesting and as yet untapped artistic playground.
As for tubes, they operate on an analog vs digital basis, thus the better bass sound frequencies in amplifiers. Steampunk, if it gets that far, steers towards analog vs digital in processing as phase change physics is also a more analog vs discreet science. Thus the argument against tubes could be an argument against the lack of understanding of where the artist using them is coming from rather then (as in some cases I’m sure) that the artist just doesn’t understand his history and think anything old can be glommed together and people won’t notice.
Basically, if someone is just totally faking it and didn’t really put thought into it, people notice.
Love that video btw Richard, here’s a couple others for you 
Abney Park
The Dolls of New Albion, A Steampunk Opera
