that the peloton can go faster now that it did in the worst of the EPO years is a dire reminder that it'll always be a race between cheaters and the doctors that come up with reliable tests
other ludicrous explanations coming from people that make a living from the cycling industry is "improvement in bike technology" (which then again is absolutely laughable)
There is also another factor that is having an huge impact on cycling performances: power meters. Power meters help a lot on energy and fatigue management and also on training in a scientific way. In the 90s (the EPO era that you are referring), pros used only HR monitor, right now pros are using PM and a lot of other sensors to track every details of their body.
I am not saying that there is no doping, but reducing the improvements only to doping is a bit silly.
I had my VO2Max tested forty years ago, and "Zone 2" training is just a rehash of Arthur Lydiard's coaching from the 60s. This stuff has been known for decades, but just repackaged with new marketing and sold again. And I'll guess that nearly every pro in the peloton had a power meter on their bike during the "Lance years". Had one on my race bike at that time.
Beside, you can collect all the data you want, you still have to do the work. I've known plenty of amateur cyclists that thought staring at power meter graph would reveal the mystery of why they suck, when the problem is too much staring at the computer, not enough riding.
the dramatic increase in power output happened less than five years ago so it's not about the gear, it's chemistry
we're seeing ludicrous numbers of about 7W/kg on long climbs like we used to see in the worst of the mid to late 90's, it should tell you that what's going on is bad