@metin I wouldn't call Matrix decentralized.
matrix.org/vector.im is just too strong within the network to have a decentralized network, IMHO. YMMV.
@ij @metin I am surprised how many people I see on non-matrix.org servers. My university provides Matrix for all students, so in my case most of the people I write to are not on matrix.org (though I recognize that this far from the average experience). And this should only improve in the future with more lightweight alternatives to synapse becoming more mature.