Like usual, Bill Simmons is an idiot.
Rebooting would set the franchise back significantly imo. They’d be a 5-8 seed with no clear star and running out of trade ammo as well. Kicking the can down another 3-4 would be awful.
In fairness, if I heard Simmons correctly the reboot scenario isn't something they'd choose - it's something they'd be forced into if Kyrie leaves - and Horford opts out. If another contender swooped in and offered Al 4 years at max money or close to it - and/or if he sees the situation here completely falls apart - then he bolts.
Horford is the one guy you can't replace because he can guard any big in the league - and presents matchup problems offensively. If he leaves, even if Kyrie returns - unless they attract Davis, the team won't be able to compete with Philly or Milwaukee.
Then you may be forced into a reboot, or roll back the best team you can and win 44 games and go out in round 1.