There’s just a teeny tiny problem with that; disabling web search renders Search unable to do maths.
It’s not an issue for me since I use PowerToys to get Spotlight-esque search in Windows, but it’s nevertheless hilarious.
macOS search is so much better than Windows search it’s not even remotely close.
It doesn’t save form inputs because when you click a suspended/unloaded tab, it reloads the whole page. Everything unsaved on that page is lost.
I really hope some day Firefox will work the way you say, though.