I hate BL

But I can see why it smashed. It was designed to smash in today's climate. ARTPOP was designed to smash on radios in 2011/2012.
"Many radio hits on ARTPOP" - Gaga
In 2012 it looked like the album was going to come out. You honestly would think not a lot had changed in a year, but considering Gaga seemed to be following the same wave of inspiration for 3 years then it makes sense why ARTPOP sounds 3 years behind.
I have no doubt that Gaga recorded progressive music though. I just think the most dated songs were chosen in an attempt to appeal to radios, while the experimental tracks were pushed aside.