Not really, I don't think. Or rather, it's not really answering the question that was asked. There are technical explanations of some topologies that you can use with some vacuum tube triodes and related parameters and so on. So there is justification for which tube to use among several options for the circuit in question. However, the explanation for using tubes as opposed to something else is this: "We've experimented with several amplification stages, but in general we like the results obtained by tube amplification." And among some of the options and observations, the language is subjective and qualitative, e.g. "The treble becomes more sophisticated" and "Other capacitor types seem to give a less transient treble."
Anyhow, it's worth making the distinction that many of the justifications seem to be based in the "what I think sounded good" approach rather than through engineering analysis. So it is left to your imagination and interpretation how rigorously the subjective impressions were determined and how valid those comparisons are.
EQ's not going to fix nonlinear distortion and quirks with the drivers, resonances, power handling, etc.
For what it's worth, check the pdf and research here. No research or impressions or whatnot is perfect, so it's worth checking the methodology and so on for yourself. Sound preference ratings depend on how people are tested, music selected, etc. of course.
Quick-and-dirty for what the graph is saying:y axis represents the average subjective rating of the sound, and each bar represents a different EQ profile, one of which is no EQ at all. All testing on the same headphones. Here, LCD-2 without EQ sounds better than using some EQ profiles (the ones approximating some modified diffuse field and free field, respectively) and worse than using EQ with other profiles. i.e. you can make good headphones sound better with EQ, at least to the listeners tested, etc.
One key reason to prefer EQ cuts over boosts is that some EQs don't have some pre-amp functionality (to lower the level) and adding boosts could result in clipping. If you're reducing the overall level by enough that none of the boosts could raise the signal into digital clipping, then boosts are fine. Inherently, EQ doesn't cause distortion, but going into clipping will certainly do that.
But aside from that, there are physical and psychoacoustical reasons maybe to prefer cuts over boosts. Trying to boost some frequencies a headphone can't really do will result in more distortion at a given volume. Also, FR dips are less obvious and objectionable than FR spikes, so there is less need to boost than cut. Along those lines, if you're using some kind of ham-fisted graphical EQ and/or are screwing things up (bad usage of EQ), there is less harm from axing some frequencies than really boosting others, perhaps.