While I don't have hard data to counteract what you say, my personal experience is that every .0 release is indeed quite rough on the battery, and within a few weeks a .1 or .2 release largely remedies that. This effect is usually visible on both older models and the newest ones (even though, for those, you don't really have a way to compare the behaviour with the previous iOS version).

I've experienced this almost every year.

So - don't attribute to malice what can be explained by a rushed release.