A2P 10DLC requires all senders to provide company/corporate information and register their "campaigns".

Which is to say, when I send a grocery list to my wife, that must be under the auspices of a business case that I have registered with twilio and the carriers and within the confines of a campaign that I have defined with example messages and an opt-out and unsubscribe mechanism.

There is a sole proprietor option which is hazily defined and it is unclear if twilio even understands the implementation of.

All of this to say:

Because of the horrible behavior of both twilio and their customers there is no longer any such thing as programmable, personal messaging.

Personal messaging is something you do with your thumbs, on your physical device and programmable messaging is spam. There is no third classification.

Twilio could have been a boring and useful telco infrastructure company providing plumbing for interesting use-cases - but there's no route to billions there so they had to somehow become a unicorn. That's where the "customer engagement" comes in.