When I look at a lot of the companies that are offering so many models of guns, it's generally slight alterations to an existing model which means it is very cheap to have different models.
It's very easy to have a medium frame autopistol and offer it in 9mm, 40, 357 sig and with each offer a 3.5, 4, 4.5 barrel.
Compare that to Smith and Wesson offering a medium frame 6 shot 357 magnum and a small frame 5 shot 38 special, it's a lot more expensive for them to offer those 2 models than it is for the other company to offer 9 models.
Also, what was once simply a variety of options for a single model is now often a new model.
For instance, back in the day every gunshop would carry a smith and wesson 357 magnum..but they may have only carried a couple 4 inch versions and a 6 inch version. Take the famed Smith and Wesson Model 27 had barrel length options from 3.5 to 8.75 in quarter length incruments, 3 different grip types, 2 different trigger options, 3 different front sights, and 2 different hammer optoins, and a couple different finishes...and this isn't covering any of the engraving options, or the fact that the Model 28 'highway patrolman' came out a short time later with just one finish, 1 trigger, hammer, and front sight type, but still 3 different barrel lengths.
The Registered Magnum (model 27) dealt with it's huge variety by being something of a special order gun, but for many years it was the only 357 magnum for sale so a gunshop would stock some of the variants that he thought would sell well. Still, no way a gunshop could afford to have even a fraction of the offerings for sale at his shop.
Now, the Model 27 would probably be broken down and cataloged as 5 or 10 different models.