These are not "themes that were common to the time period". These are themes that are common to human history, this type of camp was not invented then.
For example if you check https://en.wikipedia.org/wiki/Internment#History_of_internme...
you will find examples going back more than 300 years, and I'm sure a historian can find even earlier examples.
Internment camps of various kinds happen by EVERY war, not just this one.
> it's willful blindness to ignore the deep similarities between a policy of containing and suppressing a racial group, and a policy of containing, suppressing, and exterminating a racial group.
No, it's willful blindness to think this was unique in any way to WW2. "Camps" is NOT the important or interesting thing about that war, it is an almost trivial detail.
Your framing it that way makes it as if it was something specially important. But in actuality it is a minor footnote compared to what they DID in those camps.
It's like saying "An important note about the 21st century is that humans lived in houses. People in both apartments and individual homes had wide access to cellphones."
You are focusing on the wrong thing.