I was suggesting that photosynthesis is a very unlikely mutation to occur and thus its unlikeliness means most life, if it emerges, won't progress to that stage.
The filter doesn't have to be ahead of us, it could be some stage of development that we've already passed. Like photosynthesis, or the development of consciousness. If, out of all life that develops, only a tiny fraction ever develops photosynthesis, the universe would be largely devoid of any life that we can presently detect. Despite us being the lucky lifeform that did develop photosynthesis in our past.