Free if possible.
if it's free...YOU are the product
..or open source. I agree with your general sentiment, but OSS is a bit a different story.
Multiparty collaboration tools require servers to rebroadcast each party's contribution to the other participants. Servers require hardware. Whether running open source or proprietary SW, the HW needs to exist. Who supplies the HW?
Truth be told, each party could multicast to every other party, eliminating the need for a server. But that requires a lot of bandwidth. Each party needs N! times the single link BW. Does not scale well on home networks. Again, pointing out the need for a (centralized) server, for which someone needs to provide.
Depending on required video quality a jitsi server can easily be run from one of the parties (read: a simple consumer DSL/cable internet connection).
You could as well make a point in saying that everything using the internet is centralized by its nature, otherwise we'd have to establish p2p layer 1 links between all parties but we currently rely on the services from a few large players running the tier 1 internet.