Even with the limits. The back-and-forth is fairly quick, and longer messages are just broken up into multiple messages. Like regular conversations though, people tend to keep it short and sweet.
For business, the value of reliable delivery, timely and increased customer engagement tends to far outweigh the costs.
Aren't there cases when phone networks get massively congested and SMS are not delivered until hours later? Such as New Year, Natural Catastrophes, etc... in that sense Email delivery is superior because it's fully decentralized.
Turns out that people need to communicate during calamities and often prefer text and so do services that are delivering services to these people.