You're expected to have a legitimate version of the assets, if you don't thats your moral choice. However, some check for assets or cd might come in the installer. There's simply absolutely no reason to keep checking for CD in this day in age to be in the drive and have it cause random errors if you use a no-cd. These were some of the first things we removed because its annoying as hell, especially when developing and would likely have triggered the anti-tampering with custom builds anyway, because of a different executable checksum and memory location.