Controls for the Internet market could have been made with the Microsoft Foundation Classes, but this market requires controls to be small and compact for downloading over the network from Web servers. MFC applications tend to be large and require support DLLs. ATL allows creating smaller controls without support DLLs, so ATL is in a sense a lightweight alternative to MFC for the COM control environment.
A common use of ATL in ASP (Active Server Pages) is to construct objects that can be called from a script. Whilst limited in certain respects, VBScript is able to call C++ Windows code contained in a COM object.