CMGI and the other “incubators” of that era were nothing like YC. The label “accelerator” was applied to YC years after it was started because of the need for a generic term to describe YC and all of the clones. Whether or not that label was previously used for some other kind of business is irrelevant.

Makes sense. I suspected that might be the case, which is why I mentioned the possibility of something more specific intended. (In case other readers are struck by the same thought, it might be worth a footnote).