I agree, I was surprised to read "real raves don't happen in legal venues" - first time I've heard that line of thinking. Been raving for 20 years and here is what a rave means to me: very dancy music, electronic of some type (doesn't need to be pure edm), no judgements, kindness, love, good energy. I'd argue this is unsurprising given where the idea of a rave came from: https://en.wikipedia.org/wiki/Acid_Tests
"No judgements" is not something I would attribute to legal venues. I mean there are SOOOOOOOO many clubs with dress codes, and that's just scratching the surface.
It is my understanding that rave culture evolved out of the 90's illegal party scene which grew from the 80's acid house music scene. But even if you take it from the Acid Tests that would mean the parties were only legal for a year and have been illegal for nearly 60 years.
To some a rave is just any party, to me it refers to the event being a grassroots operation. For the people, by the people and which is usually done on the cheap because artists aren't usually rolling in dough.
To each their own though. I'm not gonna police your use of the word (unless you publish it apparently).
to me, rave is about PLUR: https://en.wikipedia.org/wiki/PLUR