I have been programming for many years now, primarily in PHP and the like and would consider myself an intermediate programmer. Some of my online projects have now gone global and very widely used, i am now in deep thought about scalability etc.

All of my systems so far are written in PHP, no known database structure such as MySQL etc. Instead our databases use an 'operating system style' method of storing information, files and folders if you will. We also do not use any outside/third-party software or CMS, so far this has work out extremely well. Most people, when they hear about the way we do things, criticize and say that is an idiotic idea but normally after seeing our systems in more dept are converted to our way of doing things.

Is it really that bad to not use a standard databasing systems and only using the one (slightly heavier than others) language of PHP?

How well on the face of it will this kind of setup scale?

N.B. Our systems include things such as account and user management, documentation development and task/project managing.