When you run 1x, aren't you basically force to cross chain?
One key difference is the design of the chainring. A traditional ring is made to allow shifting, which means there’s specially shaped teeth and protrusions that will pick up the chain and help lift it in to the next gear.
Cross chaining with traditional rings will put the chain in the angular region where it ‘thinks’ you want to shift (ie. these mechanisms will start hitting the chain plates).
On a 1x system a narrow wide ring is typically used, or a similar device, that meshes more completely with the whole chain link. Since it doesn’t have to worry about shifting, it’s only worried about retention, so it can ease the chain into a consistent position from a wide variety of angles.
As for the rear derailleur, they’re designed to rectify the angle as well, with SRAM opting for a more eccentric pulley position relative to the pivot, and Shimano using differently shaped parallelograms. Both these systems keep the pulley a consistent distance away from the sprockets, so the whole system can accommodate wider chain angles.
On a 1x drivetrain, if the single chainring was located in either of the positions of the large or small ring on a 2x or 3x drivetrain (to either side of the nominal chain-line), then yes the chain would be 'cross-chained' when on either the largest or smallest rear sprocket.
However, on a 1x system the ring is positioned on teh nominal chain line so it more closely lines up with the center of the cassette - like the middle ring on a 3x system. This obviously reduces the lateral angle of the chain when on the largest or smallest rear sprocket compared to the classic cross-chained state.
It is true that the lateral angle of the chain is a little greater compared to the smallest sprocket - large ring and largest sprocket - small ring configurations.
The more you deviate from a perfectly straight chainline, the more friction you will experience, and the smaller the rear cog you are driving, the more friction you will experience.
1x drivetrains exist because the cycling industry makes more money reinventing the wheel to lower production costs, while forcing consumers to buy into new standards.
Without continuously changing, marketing hype, and designed incompatibility, many more cyclists would be able to hobble perfectly good used parts together into functional bikes, and new bike sales would decline.