3B+ forward has support for USB boot, as of I think July this year it was built into the firmware for the 4b. I have a Zw with SD card as it requires more or less but everything lese is USB based with drives I swap around for raspbian, ubuntu, retropi/etc. But setting that up does require an SD card with respbian unless the pi shipped with the newest firmware.

I'm not against on board storage but I understand the tradeoff to allow user expandability and reduce production costs. I think they'd get heat on the eMMC size unless it was like 32gb and I don't think that cost increase would make it very far. But maybe with the push to the 400 they will start to go that route to create a self contained but expandable system that is plug and play raspbian by default.