I cannot help but think that these big tech companies (FAANG, et. al) are missing out on diversifying and increasing their engineering expertise by passing over

I cannot help but think that these big tech companies (FAANG, et. al) are missing out on diversifying and increasing their engineering expertise by passing over developers like you. There is still so much stupid money out there that it doesn't pay to do this. Literally immaterial, and it's more cost-effective to hire for a narrow-but-consistent set of requirements.