I actually did leave H!P for awhile toward the end of PE right before 9th gen joined and actually got back in right before Sayumi graduated (I still vaguely followed news on Twitter and the like).
I do love the songs and I do like following the girls' progress from all groups... and I like seeing what surprises happen (S/Mileage rebrand, new Factory Groups, etc.) but HONESTLY, I have so many friends that I've made through H!P, so really it's the community that's making me stay.