At one of my jobs we were sending millions of notifications; our Twilio bill was $50-100K / month. At that level you start caring a lot about your cost per message and do everything you can to bring it down. Yeah it's always a hassle and annoying to implement a proper notification system, but the difference is that the extra effort is a one-time implementation cost, not an ongoing one (at least not an ongoing $50K/mo commitment at least).