I would be surprized if your assumption were not correct, . . . as I have often thought the same thing.
Postulating a theorum, . . . a combination of our 2nd amendment freedom did much to keep revolvers in our hands in the time period 1850 thru 1975 or so, . . . and the lack of that same freedom took them and their overseas manufacturers out of the mix during the same time frame.
Fast forward to our global economy, . . . foreign manufacturers now make them for the US market, . . . because there is a substantial market, . . . and it coincidentally is more semi-auto influenced abroad than in the CONUS.
I would add that Mr. Ruger, . . . every cowboy from Buffalo Bill on up to Roy Rogers, . . . and Mr. 44 mag himself, . . . Clint Eastwood, . . . also helped shore up the revolver as uniquely perfected here in the US as well.
Anyway, . . . just my $.02, . . .
May God bless,
Dwight