This is the big thing that Microsoft understands. For a non-tech company, it's going to be pretty hard to get buy in to pay for ChatGPT enterprise, and then pay for/spend dev or IT resources to integrate it (and develop those integrations) with their already existing Microsoft/SharePoint/Teams stack to make it useful. And then you still don't get the convenient Office app add-ins.

Microsoft bundles this all, integrates it for you, and provides a GUI for governance controls. It's very click-ops focused, which enterprise IT likes, and the bundling means you don't have to sell those with the wallets on buying extra third party tools. Nobody every got fired for buying s/IBM/Microsoft