I've done several no hop brews. Just brew whatever and leave the hops out. None have spoiled.
My SKS (Some Kind of Stout) was an extract brew with no hops. I drank a year old bottle of it and it was fine. That bottle had been in a box in back of the closet. No light, never opened once bottled and no disturbance.
That horrible swamp water I made from licorice candy didn't have hops. It was terrible for many reasons, but not spoilage from lack of hops.
I'm fairly certain Triple Berry Beer didn't have hops.
No hops in my mead or apfelwein, but neither of those are beer.
Kungaloosh was all fruit juices and light DME. Pretty sure that had 3 pounds of light DME. No hops and no spoilage. 14% abv may have acted as a preservative
I think part of why back in the day hops was used to preserve beer was their lack of storage options. They didn't always have air tight and completely sanitized glass bottles. They didn't have climate controlled houses. Back then, they were storing beer in clay pots and wooden barrels that were shoved in hot hovels and toted around in rickety wagons. They didn't have the same ready access to clean water then either.
I'm not arguing that we don't need hops any more. Just that we don't need them as much.
Trivia bite. Rosemary has been used instead of hops.