There is no processor feature of a modern CPU that doesn't give advantage to all the operating systems that use it. VT-x virtualisation, AVX, AES-NI, ARM Neon: all are used by MacOS, Linux and Windows.
TEEs (SGX+MEE/TrustZone/SEV, Google Titan, Apple T2) serve similar purposes and have similar flaws (like permanent exploits) and trade-offs (same CPU -> side channels, uarch complexity problems, different CPU -> cost; separate chip -> heterogeneity, cost). It seems like the Titan/T2 approach leads to higher security, but I'm not sure that is settled yet. A new arch like RISC-V could do better (though it doesn't look like RISC-V will do that). I would love to see hardware support for micro/nano kernels, but that seems as far away as ever.
Obviously it is good to have a guaranteed client for your chips, but I can't see it stopping Intel if shoestring outfits can build something like RISC-V.
It also makes it easy to add specialized accelerators and processor instructions that you can then build support for in the operating system you ship.