I missed where anyone said it had to do with design, my point was that in Europe people have always had more confidence in smaller calibers than we did (Until recently).
Even after the .380 ACP became common the .32 was the handgun of choice in Europe, and I doubt it had anything to do with accuracy either, I mean, we are talking about Europeans here (By which I just mean Europe has never had the gun culture America has, and target shooting begets accurate shooting, all else being equal).
So, with the choices of blowback pistols being .25, .32 and .380 I believe the .32's sold more by a huge majority. It may have to do with ammunition costs in Europe in that era, but I think it was just the fad cartridge of it's day.
Sorry, but wasn’t sure on your post, so posting this for clarification/expanding my original post.
It was stated that was why .32s were so popular prior to World War Two... I disagree that it had any reason for shooter proficiency at that time verses now.
Smaller caliber guns were popular back then due to what could be done when companies started to consider things other than revolvers. First, ammo was very inconsistent back then. Blowback is more forgiving for that type of ammo source, especially in what we would call smaller calibers (under 9mm).
Blowback is very simple, so that was widely used. Designs for handguns at the turn of that century also weren’t narrowed down to what would become standard (look at the Luger and C96, and compare them to what is commonly produced today). Until locking systems were standardized/proven, you really couldn’t go too far past .380 in blowback, unless you made the slide/recoil spring so heavy that it wasn’t a marketable pistol. That is what made these guns so popular, which includes the ability to make them affordable. While we had the 1911, what smaller reliable pistol was out there that didn’t use a blowback action? Even a good number of full size pistols were finicky up to somewhat recent times.
While I don’t mind discussing history like this, I can’t really leave a comment that people were better shooters at such time, so guns were produced to fit that. If that was the case, we likely wouldn’t have moved away from revolvers. Proficiency may have stemmed from .32 pistols, but I am pretty sure Browning didn’t go, “all these people out there are such awesome shots... maybe I should design a blowback pistol in .32 to utilize that proficiency.” It was probably along the lines, “hey, I can make a .32 autoloader that could be somewhat smaller than common revolvers, and allow for quicker reloads from a magazine.” Accuracy is a standard that all manufacturers set out to do better than their competition, so it is hard for me to accept the original inference that I quoted.
For people that are interested in this, go on YouTube and look up C&Rsenal. They are currently doing videos on World War I firearms, but to warn you, some are pretty long (just shy of two hours; one of the Pedersen Device is probably one of the best videos ever done on them). I bring that channel up because a lot of .32s were produced at that time, as well as used in that war. They have a few videos, such as the Ruby pistol (also did a few Browning .32 designs, and a few European models), which also goes into the specifics on why these guns were produced, which I feel is definitely a better way to answer that question than a subjective statement about practical accuracy. They also do a good job with giving enough background regarding the competition, and do point out main differences between what we look for in a carry gun today and what people looked for in the early 20th century.