Need? No, of course not. But it simplifies an assortment of things and once Matter is more broadly adopted, setting things up fully local will be a massive improvement and future-proofing.

The big players are signaling that they are not making money on voice, so I'm expecting them to start charging or give up (typical Google answer).

A few of my use cases:

• Litter robot is in error or offline state for 30 minutes, toggle power
• Easing of light intensity and color as sun sets daily
• Vacuum when we're gone and it's between allowed hours.
• Return vacuum to hub when we return home
• Turn on lights so vacuum can "see"
• Improved environmental control because I have better presence detection using HA than Nest.
• Turn off power for cable box if conditions are met (otherwise it's nightly updates and reboot illuminate the bedroom at 3 AM.