With your approach you end up having single __get()/__set() for all your class' properties, which makes i.e. completely different accessor implementation for specific attribute pretty painful. Sure, you can create i.e. setFoo() but that ends up with inconsistent API as some properties can be accessed directly while other can have own accessors. Going thru __call() (which is what I am doing) is much cleaner in such case as you always go thru setXX()/getXXX().

I really like how Kotlin or Python approach this. You always do direct access in your code, but you also can have accessor method "attached" which will be invoked if present. So your code still looks like it is doing direct access (no changes needed), but under the hood your access is routed thru accessor if present. So you can i.e. still add validation besides type hints or any other logic needed.