Comment by thunderfork

Generally "small patches" and "well-compressed assets" are on either end of a trade-off spectrum.

More compression means large change amplification and less delta-friendly changes.

More delta-friendly asset storage means storing assets in smaller units with less compression potential.

In theory, you could have the devs ship unpacked assets, then make the Steam client be responsible for packing after install, unpacking pre-patch, and then repacking game assets post-patch, but this basically gets you the worst of all worlds in terms of actual wall clock time to patch, and it'd be heavily constraining for developers.