>>Please see my reply to Victor because I don't want to post the same reply here. (re: bricking)
If your mom did try to upgrade her phone OS and something went screwy, the network would be peeved, she would be peeved, and the manufacturer would be blamed. Whereas if they "orphan" the OS the whole issue goes away- and I still can't see any victim, least of all your mom.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1