It goes farther back than that.
https://en.wikipedia.org/wiki/Left–right_politics#History_of_the_terms
Nonetheless, the terms "left" & "right" mean what they mean as we use them today, their multiple definitions notwithstanding.
Note that here on RF, I observe those who identify as socialist (by posting in that forum) identify as "left".
And fascism has been very much alive in socialist regimes.
This is simply untrue.
The "average libertarian view" doesn't justify "all abuses" in defense of private property.
Moreover, you still aren't addressing this problem of "right" meaning both economic liberty & fascism as is being claimed by some.
If anything, to say fascism is only right wing appears to be an attempt to sanitize left leaning fascists, eg, N Korea, the old PRC.
It doesn't shut down any discussion to simply recognize fascism for what is, ie, extreme control of the populace.
I know my commie friends loathe dictionary definitions, but they truly do reflect common usage.
Looking at.....
http://www.merriam-webster.com/dictionary/fascism
We see.....
- : a way of organizing a society in which a government ruled by a dictator controls the lives of the people and in which people are not allowed to disagree with the government
: very harsh control or authority
You could argue that the definition you use is superior, or that dictionaries are wrong, but there are these other (than yours) definitions in use nonetheless.
Thus, there is great ambiguity in the the terms, "left" & "right".