Short code isn't automatically more simple. For example, you put your secrets directly in this file instead of environment vars or memory or a config file.
Then what if you want to add a Twilio library? But then the original author updates the single file, and you want to pull the changes? Very complicated.
Every good software project is concerned with maintenance, not writing the fewest lines or having a single file.
Also, as someone who has written PHP for 20 years, I don't know what "idiomatic, old-style PHP" could mean other than "bad code".
