$include(file2.asm)
...
Now, tell me, is it really HARD to figure out what has been included and from where????
Very hard, the file could be obtained from whereever the particular toolsets default convention would search for it. If you have a look at Keil uVision (which I do not use - thus stated by recollection) you will find that include files may be found in, at least, 5 places. In my build, include files are fetched from 3-8 places.

If you are under the belief that the Metalink emulator is specifically designed for the Metalink assembler you are wrong. My guess would be that, of the users of the Metalink emulator, the percentage using only the Metalink assembler would be a single digit.

Erik