We strongly recommend developers to upload a DRM free version of their game. If their game is available on Steam then you can include a Steam key for people who want to access those features. We do make exceptions for some games to sell only Steam keys but there must be a reason like the game requires Steamworks to be functional.
Regarding the upload size, I've removed your upload limit. For larger games we recommend developers to use our command line upload tool: https://itch.io/docs/butler/. It's significantly more reliable than uploading in your browser, has a higher upload limit, and will only upload delta patches.