It probably is, but I wonder how much one needs time at research conferences to produce interesting work.
The word "wonder" is very deliberate here: I genuinely have no idea. In English lit, my own field, access to a research library (with peer-reviewed articles and books) is far more important than conference attendance, for example.
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...
I've actually found conferences quite useful for intellectual networking, although I'm not really an outgoing person, and it's not my personally preferred approach. I'd rather have some robust mailing-list communities, but they don't exist in all areas, and many people pay relatively scant attention to mailing lists. I do do most follow-up and collaboration over the internet, but in a number of cases with people I met at conferences.
In particular, I've found showing up at conferences to be a way to get your research onto people's radar who didn't previously know about it. Just by being there, and especially if you also give a talk, it can make people think of you as part of the X Research Field, and remember that you did some research on Y. In turn they're then more likely to engage with it, cite it, mention it to others when it's relevant, and maybe keep you in mind as someone to potentially collaborate with (if research interests align). All that could happen completely passively, by putting your paper on the internet and hoping people find it in a Google Scholar keyword search. But that's relatively low-probability. You could also try to approach people online, but "cold-emailing" people about research often ends up neglected, since people get a lot of email. Conferences by comparison give a setting where people are expecting to hear some talks and exchange short "what I'm working on" pitches over coffee or dinner.
I think it might even be true outside academia. Some startup/tech events are very focused on business/career networking, but others, like SuperHappyDevHouse, are great for intellectual networking.
I'm not precisely sure myself - in CS, though, a lot of the research is digitized, and much of it is available for free online (if you know where to look - Google Scholar really helps), but as far as making useful research contributions goes, being able to provide citeable papers helps, and most of those are published at conferences.
