Blackberry made regular slab phones too and they were massively outsold by the keyboard ones. Why would anyone buy a slab phone running an obscure OS that lacked any major apps, when Android and iPhone were available? The keyboard was always the selling point.
The fact of the matter is that the smartphone market could not support more than a few players. Blackberry was just one of several vendors without vertically integrated supply chains that disappeared: HTC, Nokia, LG and Sony all abandoned the market as well.
You’re operating with massive hindsight bias here. It wasn’t a foregone conclusion in 2007 that iOS and Android were going to win. BlackBerry (and indeed many of the players you listed) had a chance to compete and they simply didn’t. Also I’m not sure where you got the idea that BlackBerry didn’t have a vertically integrated supply chain. They absolutely did. I worked there in the mid-2000s and the hardware was manufactured literally down the street from where the OS and apps were built.
The fact of the matter is that the smartphone market could not support more than a few players. Blackberry was just one of several vendors without vertically integrated supply chains that disappeared: HTC, Nokia, LG and Sony all abandoned the market as well.