CS is a bit different in that conference proceedings are where a lot of the peer-reviewed papers are published. E.g. in graphics, SIGGRAPH is the top place to publish, and in HCI, the same goes for CHI. So attending conferences to present papers is part of the process of getting papers published. Journals do exist, but tend to be used for big archival papers: you might take 3 or 4 years' of conference papers on a project and wrap them up into a giant 40-page journal article for posterity. But they aren't really where recent research is being published & read.
Admittedly that's less true in some areas, where journals do have a larger role. For example, in machine learning, while it's common to publish at conferences like ICML or NIPS, it's also perfectly fine to skip them and just submit to JMLR (http://jmlr.csail.mit.edu/).
Journals do exist, but tend to be used for big archival papers: you might take 3 or 4 years' of conference papers on a project and wrap them up into a giant 40-page journal article for posterity.
That's the polite interpretation, at least. I'd say the pattern I see more often is that the exact same research gets presented repeatedly at 3 or 4 conferences before getting published as a journal paper. Also, the research was probably done by 1-3 people, but an entire group of 6-10 people will have their names on all the papers...
Admittedly that's less true in some areas, where journals do have a larger role. For example, in machine learning, while it's common to publish at conferences like ICML or NIPS, it's also perfectly fine to skip them and just submit to JMLR (http://jmlr.csail.mit.edu/).