It didn't work that well for everyone (except the established vendors), otherwise it wouldn't have taken the market by storm. Modularity is a good thing to have for innovation. If we're returning to "fixed sets", that probably signals the exploratory period is dying.

Anyway, "general computing" doesn't necessarily mean mixing and mashing hardware. But it definitely means executing arbitrary software with full control over installed hardware. The trend line here is definitely from "more" to "less" of "general computing". We've started with raw metal and hardware diagrams being included in the instruction manuals; then diagrams disappeared, CPUs gained abstraction layers - but it was still fine, computing-wise. But now we're in era of OSes and even CPUs limiting what users can do with them, and multiple parties owning various pieces of a computer, with nothing left to own for the user who actually buys the machine.