It's basically been true along every step of the the poker bot evolution (HU limit, HU NL, and 6-max NL) that the bots donk a lot more than the humans. 10 years ago you could find pros arguing that donking in any situation is always wrong. That's been shifting for years, but still not to the level that the bots do it.

My personal belief is that the "no-donk" strategy is an adaptation by fallible human minds to reduce the branching on the decision tree to something tractable.