At first it was all about presenting data in an original looking way. In the end it was about pushing political ideas in your throat using a plain bar graph. It was not about sharing something interesting you found but about taking advantage of a captive audience.
/r/mapporn is another one that has gone down the spiral, it has a lot of the same problems as /r/dataisbeautiful.
I think the one that frustrated me the most was /r/data_irl, where about half the people in there take the sub’s name literally for some reason and think it’s for actual data in real life, and not a data version of /r/me_irl