Optical zoom and thin form factor doesn't work together too well.

Huawei P30 Pro uses a 'periscope' style design (using a mirror to put the lens alongside the phone's back instead of back-to-front) to get 5x optical zoom, so it can be done

I was surprised by this as well - the ultrawide certainly seems more niche than a 3x or 4x for better portraits, attempts at wildlife, etc.

Actually I'm a wide angle buff myself. 13mm is a very nice addition IMHO.