It had NOTHING to do with the simplicity of the parser. He's said in his lectures that the real reason was that he wanted to prevent someone hiding custom pre-processor data in the comments and causing incompatibility.

I think this was stupid. First, it happens anyway to some extent with people just using custom byte encodings for "strings". Second, using comments for metadata could be useful -- even if optional. For example, adding types after strings to specify things like the date format.