Tumblr has recently (actually, not so recently any more) disabled commenting on their platform. My partner is part of a relatively close running community that used to use Tumblr to connect with others, give/receive encouragement about their runs, and so on. Since they disabled comments (with some half-hearted promise about bringing them back, well, sometime) hardly any of her friends post any more.

Since, as this article says, Tumblr's business model is depending on people using it, removing comments (in favor of pushing people toward reblogging) seems ill-advised.