Why do official people tend to use Bijoy Bayanno instead of Avro?

Avro keyboard is objectively easier to use as it supports the phonetic keyboard layout for Bangla. Bijoy requires you to learn its specific keyboard layout. Moreover, Avro is open source which Bijoy Bayanno is not.

Why do people still use Bijoy Bayanno over Avro? I've seen my parents and every other employee in their office to only use Bijoy Bayanno and not Avro. Why is that?

Is it because Bijoy Bayanno was released earlier and old people don't like change?