Yes, of course they should. But I can see why people sometimes just find it convenient to use their own phone, and then it becomes a habit.
And my impression has been that the government is VERY slow to adapt to new stuff. Back in the late '90s, people who worked for the SEC didn't even have email. So John Reed Stark, who was trying to bring them into the late 20th century, opened accounts at SI and RB. His office used them to make announcements and accept tips.
And not all companies required to report were making disclosure on Edgar till around 2000.