these are the only two options, I’m sure we’d all ideally like both done properly but would you rather your group have a decent amount of music released but it never be promoted along with the group resulting in great and maybe ok charts but your fandom not really growing and your idol never having new opportunities to expand OR not as much music and year round promo resulting in continuous chart toppers, a growing fandom and plenty of other content?
I’m trying to see something
First of all, it really seems like you lack understanding in how music business works, if you think those are only two options.
If you pay attention to charts and album sales,you'll know why there are so many comebacks and why agencies are more invested in touring than standard marketing.
Second of all, you forget that extensive promoting doesn't result in better sales or chart placements.
Agencies work on low cost/high profit principle,it's how business works. Doesn't really have to do anything with fandoms.
Third, every aspect of creative content is regulated by agencies, unless you are independent. Unless they ask you to produce tracks, you can't claim any rights or royalties from tracks, other than what percentage is written in your contract.