People who submit to and review for conferences have known for quite some time how random that process is. Also they are slow. In a field that advances leaps and bounds on a monthly time scale, holding a conference half a year later or publishing a journal article more than a year later is just equal to irrelevance. The reason conferences still matter is because of legacy systems that are slow to adapt to the new reality (and because of networking opportunities).
But actually, thinking back, 10 years ago there may have been more of a stigma around a paper that was only on arxiv.
But actually, thinking back, 10 years ago there may have been more of a stigma around a paper that was only on arxiv.