Playlisting can help but it is only a bit. If the song is not good or people have just moved on, the song isn't even going to chart or will drop quickly.
Except for NJ, the newer groups have about the same level of playlisting. Because to get above say 35M you can't just go out and buy it, you need to get past a certain threshold of ULs first and be able to hold at that level.
Its not like Korea now, where you only need 100 ULs to top 20 and 200 ULs for top 5, and its almost nothing for a song to stay in the top 100 indefinitely. Thats why you got songs doing really well in Korea but are mega flops globally.