I'm speaking specifically about Western classics (esp. Roman).

Which centuries did you have in mind? In what countries were these purgings? Which authors were purged and by which sects of early Christianity?

I ask because "Early Christianity" as a period ends with the First Council of Nicea, and Christians before Nicea were (a) not at all unified and therefore had very different opinions on things like pre-Christian literature and (b) not very politically powerful and therefore unlikely to have had a major impact on book survival.

If you have specific citations for when and where these systematic and catastrophic destructions are purported to have taken place I'd love to hear it, otherwise I'm more inclined to chalk it up to "most texts don't survive from most eras for all kinds of reasons".

I'm talking about Christianity from Theodosius up until the high middle ages. So "early Christianity" is indeed not correct.

And the rest of the questions?

My understanding is that the idea that Christians destroyed vast numbers of ancient texts was heavily exaggerated by anti-Christian polemics during the Enlightenment. There were some isolated instances, but even some of those, like the Library of Alexandria, were much less significant than the polemics assumed. The Library of Alexandria had already largely fallen into ruin and disuse by the time Christians are supposed to have gotten to it, and the works left there had already been copied all over the Mediterranean anyway.

The other problem with this line is that it ignores the enormously important role that Christians had in preserving large numbers of texts. Did they selectively preserve texts while allowing others to disappear to time? Probably. But when each copy has to be transcribed by hand, it's to be expected that what survives is the stuff that the people responsible for preserving texts thought was most important.

It would be very unfair to accuse someone of burning books just because they didn't manually copy everything that had ever been written and instead only copied their favorite texts.

I would say that material decay, neglect, economic collapse, war, and changing cultural priorities played a far greater role in the loss of these texts rather than the ones lost to zealous Christians. It's just weird to single that group out when their actions represent a minority in the overall loss of these ancient texts.