With Visual Studio for example, it's not only about merging files, but installing various DLLs (for the runtime - vcredist*.exe), COM objects, .NET stuff, etc.

With Visual Studio for example, it's not only about merging files, but installing various DLLs (for the runtime - vcredist*.exe), COM objects, .NET stuff, etc. Also creating (if possible) proper uninstalls. VS2008 runs some SQLserver, PDBserver, and who knows what else (run ProcExp and see)