It took around a year for a solo dev (and a couple contributors) to develop a fully federated platform. Why is it taking one of the largest companies on the planet this long to make such tiny changes that are useless anyway.
And why are they releasing it like this instead of releasing everything at once?
Tumblr's backend has been passed between several companies* for several decades, it's a miracle it still works and can be updated
*some of which don't even know what tumblr is