I think you hit the nail on its head. There's also the fact that there's no hard line between the "vendor-ops" and the "real programmers". Rather, it's a continuum, and one crucial skill is knowing when to use someone else's tools and when to write your own. And when you do, the experience of having used external libraries and frameworks can be very useful.
Otherwise if you want to write everything from scratch, you can always write embedded firmware for 8-bit MCUs. It better be in assembly, because otherwise you're just doing "vendor-ops" with a external IDE and some company's compiler. Although technically, you're doing "vendor-ops" for a chip made by someone else, so maybe you should make your own soft core in VHDL and use an FPGA... At some point either you'll be making your own transistors because that's the only way to be a Real Engineer, or you'll accept that there's no problem depending on external vendors as long as you understand how to use the tools you have.
Otherwise if you want to write everything from scratch, you can always write embedded firmware for 8-bit MCUs. It better be in assembly, because otherwise you're just doing "vendor-ops" with a external IDE and some company's compiler. Although technically, you're doing "vendor-ops" for a chip made by someone else, so maybe you should make your own soft core in VHDL and use an FPGA... At some point either you'll be making your own transistors because that's the only way to be a Real Engineer, or you'll accept that there's no problem depending on external vendors as long as you understand how to use the tools you have.