it's part of marketing at the end of the day . If not , how do you explain in general , single sales for Johnny's are much higher than albums ?
if you bother to do some decent form of research in the 1st place , you should know that for each single release by every single Johnny's group , you will not find the same tracklist for each edition pertaining to each single release
there're exception cases but that's generally how it goes & it's not as though someone pointed a gun & said that you have to buy their singles to begin with