I believe a lot of negativity comes from people who believed the OSS preachers "come come, you don't need that proprietary crap, we have everything free and better"
And then most people are in for a surprise, that usually the above is only true in theory. But in reality there are driver issues, missing firmware, outdated repositories, broken updates ... critical missing features and in general a need to understand technical details with no polished UI.
And speaking of, with OBS I really liked the UI to just get started, but performance/quality of produced video was way worse for me, then simple screencapture with ffmpeg.
But many OSS programs are awesome, and OBS is one of them.