There's absolutely nothing wrong with it in principle.

It's only that as the web grew up, and websites became less a bunch of static files and increasingly an application, or more commonly a pile of application-like messes run by many different people at the same time, involving a bunch of dependencies between files, whether organized code or haphazard things piled on things piled on things, doing staged releases comes to be the more sensible option.

At a certain level of complexity, FTP can become a liability and cost you business.

There appears to be a vocal group which suggests their way of doing it is best, even if it involves trudging through configuration documents that remind one of engineering schematics.

Not knocking down the many brilliant developers who work this way, but it seems the simple approach sometimes is the best approach.