Oh this definitely happens all the time. I was an early employee at Clarifai, which won imagenet a year after alexnet and we were able to stay on the frontier for about 2 years before a bunch of open source models were matching our results. It was always some random PhD research project spinout or some random kid in Boston named Alec Radford.
We had a bunch of things that we never published that ended up being major research findings years later at top conferences.
We had a bunch of things that we never published that ended up being major research findings years later at top conferences.