For me the opposite. I would have never though that there would be a point to trying to "detect" DOSBox since it would be trivial to do so. After all, DOSBox is not really designed to run MS-DOS, but its own DOS-like thing, and there must be a million small details that you can use to distinguish it from MS-DOS, if you really wanted to. I mean, the default filesystem is not even FAT...

_Even_ if you run the MS-DOS kernel in DOSBox, the builtin DOS literally leaks through in many places (e.g. many API services still available instead of crashing), with only some of the more recent forks even trying to hide it.

DOSBox-X might fake it well enough.