I know I am just a random nobody to you, but I'm not satisfied with this response. If you have exhausted all options, then you need to be working on updating your resume. Your boss might not have enough juice to push this through for you, and in that case, it's probably better that you find a new job. I don't think you've exhausted all options, I think you came face to face with the reality of the corporate workforce, the reality is that most people are trying to get by with "good enough." They are afraid of the implications of you outworking them and making them look worthless, or you automating something so much that it cuts the departmental budget. If what you're saying is true, and you can reduce hundreds of man hours, then you should fight for your ideas. Know that fighting for your ideas doesn't mean that you will be praised from day one. People will poke and prod, criticize, kick the tires, make excuses, etc. Stand by your work and always come back to the table.

"Okay, I heard your proposal on how to validate data integrity in the event that we become a multi-vendor environment. I understand that parsing/wrangling data can be challenging. However, in the event that our environment adopts XYZ infrastructure, I am using tried and tested industry standard modeled languages. All major vendors support this language model, so it would not require a complete re-engineering.

life is too short to work for shitty bosses man. But don't spend time feeling sorry for yourself.