Work with any company of a reasonable size and you’ll likely be presented with a style guide.
Style guides for writers can be quite long. They give you instructions on the length of headlines, the use of images and other visual content, the number of words you need to write, the phrases you must use and mustn’t use, the tone of voice you should aim to achieve, and so on.
Honestly, they are a nightmare. A pain in the rear for any self-respecting writer or copywriter.
So why do companies create these ghastly guides? Well, they are aiming for consistency in the writing on their websites. They want everything to look much the same and to be written with more or less the same tone of voice.
Plus there is often some nonsense put in there by their lawyers.