The IBM PC was what everyone outside a few niche companies copied. IBM Simon beat the iPhone by over a decade and probably could have been significant with a few iterations. Almost every modem used to connect to the early commercial internet slotted into an IBM clone. They built the wagon, but every time they had to make a choice on how to proceed, they chose poorly.
Microsoft spent a long time resting on its laurels before starting to innovate again, but then they fell back into their old ways. Every smart move is hampered by the continuing need to subsume innovation to serve a desktop OS monopoly with declining relevance. LLMs are headed away from the silos that birthed the revolution toward on-board purpose-built LLMs that are entirely within the user's control, so Copilot's days are numbered. Even integrated GPUs will have enough power and memory to run the better LLMs in 5-10 years.
Apple: back to selling overpriced PCs. Bringing SOCs in from mobile to the desktop is an interesting move, but Microsoft and Windows PCs are likely to beat them on price and features once that world catches up. They're in for a period of mistaking profit growth for innovation the way all big companies do. The pivot to services will be fraught, hindered by corporate inertia, and possibly kill the company. They've had on-board ML cores in all their mobile devices for years, and the best they could do was Siri.