It's been a long time, but I don't think that's exactly true. The resource fork simply became optional, assisted by later versions of MacOS, which let applications open files which didn't have one.
Ahh hmm OK, I'll have to check into this some time. I feel like the filesize would stay the same (suggesting no loss of data), but it's totally possible I'm misremembering considering how long it has been, hahah :)