To explain this mega-pattern I start to the bottom: in the past we have had blacksmiths that build their own tools regularly, it was common in chemistry industry produce in-house any "glass made lab equipment", it was common between carpenters to build most of their tools, these were mostly made of wood and blades are made by the nearby blacksmith that also buy wood stuff from the carpenter and I can keep going for long. Now without tools essentially designed and made by very few subjects (yep, there are tons of electric/pneumatic/... tools producers but they do not really produce them, only design few aspects around pre-made components) nobody can work anymore.
In IT it's no different: in the past we have had many different architectures, software etc, now anything is built essentially around ARM or x86 and mostly around very few key software components.
Long story short: most type of companies you identify are not free player of a free market but only lego player that depend on lego brick suppliers that are more and more few, more and more powerful.