> it seems like hardware engineers have a fetish for all-encompassing painful vendor specific IDEs
Hardware engineers feel pain just like you do. The reason why they put up with those awful software suites is because they have features they need that aren't available elsewhere. In particular, they interface with IP blocks and hard blocks, including at a debug + simulation level. Those tend to evolve quickly and last time I looked -- which admittedly was a while ago -- the open source FPGA tooling pretty much completely ignored them, even though they're critical to commercial development.
If you are content to live without gigabit transceivers, PCIe controllers, DRAM controllers, embedded ARM cores, and so on, I suspect it would be relatively easy to use the open source tooling, but you would only be able to address a small fraction of FPGA applications.