doesn't this require you to nail down design requirements? If the designer gives a few different comps to try out, or wants to A/B test something, they'd have

doesn't this require you to nail down design requirements? If the designer gives a few different comps to try out, or wants to A/B test something, they'd have to align those changes with both backend AND frontend people to make sure they both know what the changes are. If the data dictates exactly what the frontend should look like / placement of content, shouldn't the backend just send styling / html / app code directly, and just skip frontend completely?