There will always be people out there who decide they want to use e.g. the latest stable release. Not having a guide on how to achieve that in the most intuitive place doesn’t make those people go away; it just makes things a bit less convenient for them - and likely sometimes means them coming here to ask, and others spending time answering the question (again and again).
Probably the stronger argument, though, is that the guide can show them how to do it correctly, which means them being able to change back later if they change their mind. If they don’t know, they might end up breaking their install, which will be inconvenient for both them and their community.
If INSTALL-cloud.md has a section on changing branch, it can clarify what the default is and why, making clear that the default is the most widely used, and the easiest to support.