You have almost realized that it's easy to say whatever you can imagine. There is no barrier to the one who knows how to type, with the vocabulary to express his imagination.
I may sound like a broken record, but what you still fail to understand is that the only thing that give the words value and real world meaning are facts, evidence, and empirical observations. That's how intelligent conversation is supposed to work, without all the irrational fallacies and rhetoric.
You still think the answer is to quantify the positive gains, when the question is establishing whether the gains are neutral, positive, or negative (and under what conditions and pre-conditions) beyond mere theoretical speculation and hope and belief and rumors.
On the topic of training, it is not a few lab tests on amateurs, but the empirical observation and 100% correlation of training with predictable and immediate empirical observation of performance improvements for both amateurs and elites alike, applyling the rudimentary but proven scientific method of trial and error. No elite athlete has ever succeeded without training, and the physiological mechanism of overcompensation is well understood, and measurable -- with a stopwatch -- by both scientists and coaches alike.
Even then, past a certain level of fitness, just like doping, additional training can be neutral, and even detrimental, depending on the training. For example, with altitude training, we saw that a high-high group regressed (insignificantly), while a high-low group improved significantly, after 4 weeks at altitude, despite both making significant improvements in VO2max. (Note, that in this case, as we have already discussed elsewhere, the scientific "proxy" of VO2max failed to predict the corresponding performance improvements, underscoring the scientific need to measure time trial performance at racing speed, rather than proxies that loosely correlate with race performance.) Other common examples are over-training leading to burnout, or worse, overuse injuries.