Some /24 are more critical than other. There is a price to security and for sure advertising only /24 is probably not viable. The article mentionned that some

Some /24 are more critical than other. There is a price to security and for sure advertising only /24 is probably not viable. The article mentionned that some networks within the /19, in this incident, were critical. So yes, I believe that every businesses should advertise /24 for their highly critical infra. They can advertise /19, /20 and so on for the less important networks. No need to use /24 for everything.