Thread drift warning: You'll notice I said "most", not all. The buscadero rigs as worn in Hollywood westerns aren't really seen in historical photos. In the article you referenced (https://truewestmagazine.com/low-slung-guns-invention/), he's showing low slung holsters more so than a buscadero style. Even the first picture of the Arizona marshal, while technically a buscadero style, is still worn at the same height, about hip level, as a regular holster on a gunbelt. Remember that photographs were still pretty expensive and more of a novelty back then and that folks tended to dress up and more or less show off, a dandy if you will- what we'd call glamor shots today. Sorry, I don't think the author really proved the point he was trying to make.
If you've ever worn a low slung handgun you'll have noted that they tend to move around, bang into stuff, catch on things, etc.; it's why thigh holsters aren't particularly popular in the military or with law enforcement today. They were used in the early part of the Afghanistan and Iraq wars due to the use of body armor but you'll notice that most got shortened (ex. the Safariland 6004 series usually had the top leg strap removed and the drop strap shortened) or soldiers started putting their issued handguns in magazine pouches or holsters on their vests (your own Prince Harry carried his P35 in the MOLLE loops of his body armor which was pretty common as well). Unless the gun is well secured, a low slung holster will also allow the gun to fall out, especially with the rocking motion while riding. I don't see a leather hammer thong securing a gun well enough for a working man, especially given a Colt was about $17 and a working cowboy was making $20-50/month (ammo was also quite expensive).
Bonanza was entertainment and the reasons for the set and prop choices, which the other poster questioned, would have been director/producer's choice (which I mentioned having read an article about), ease of audience recognition (if you watch Hollywood almost everyone used a Colt or a Winchester despite there having been plenty of other firearm manufacturers at the same time), use of the common 3 in 1 blanks, what the prop department happened to have on hand or any number of other reasons for their choices. I don't think anyone would consider it to be historically accurate.