Those have more marketing behind them, therefore getting more exposure.
Also in Japan, most of the battle manga are all in the same handful of magazines, and the slice of life series are in different magazines. So if your manga is in the same magazine as the popular series, then you have a chance of getting more exposure.
It’s like back when people used to watch regular TV, if your show was on a popular channel, and on a popular block of shows, then more people would have watched it, compared to some show on a less popular channel coming on at midnight.