Use of "decimation" by a purportedly educated person to mean "devastation" sounds and is IGNORANT. It is a public school phenomenon and its user should not be proud to claim he accepted public school limits without looking beyond what he was presented there. It is not a matter of "purism" in this case but of random use of adjectives because one doesn't know what a word actually means and decimation sounds kind of like destruction and some of those other big words and, gee, youse knows what I mean anyways.
New World Dictionary of American English:
decimate -- 1) (orig) to select by lot and kill every tenth one;
2) to destroy or kill a large part;
3) (obs) to take a tenth part of
American Heritage Dictionary of the English Language:
decimate -- 1. To destroy or kill a large part of (a group);
2. a. To inflict great destruction or damage on;
b. To reduce markedly in amount;
3. To select by lot and kill one in every ten of;
USAGE NOTE: Decimate originally referred to the killing of every tenth person, a punishment used in the Roman army for mutinous legions. Today this meaning is commonly extended to include the killing of any large proportion of a group.
Mirriam-Webster:
decimate -- 1 : to select by lot and kill every tenth man of;
2 : to exact a tax of 10 percent from;
3 a : to reduce drastically especially in number;
b : to cause great destruction or harm to;
Shall I go on? There are dozens of others, up to and including the Oxford, which, by the way, doesn't even include the archaic definition except as a footnote "more or less totally superseded" by the modern usage.
So are YOU the authority or are you simply some smarmy, smug, self-righteous word nazi who thinks he knows something nobody else does? I know full well the etymology of the word. But I also know its CURRENT usage, you know, the one that ISN'T 2,000 years out of date.