Yeah, the IMAGERY of the Disco Era---meaning the exaggerated stuff in movies and magazines---has now replaced reality for anyone who wasn't there.
About all anyone who actually lived through it remembers as being a "daily manifestation" were wide lapels and neckties (shag carpet existed long before 1977).
The rest could only be seen only by choice, pretty much, by going to dance clubs, or watching movies or TV which exaggerated everything.
Oh yeah. Brick-shaped moustaches. They were also popular.