This 130+ post thread tends to disagree…
The majority of players in that thread were crying out for Blizzard to address the issue of heroes being able to farm unattended whilst their players were AFK or asleep. This change does precisely that.
Pointing out that what you’re reporting isn’t a bug, and is a change that is highly desired by players that are against AFK players cheating their way to XP / items / gems isn’t flaming.
Other than wanting to be able to AFK farm, what possible reason would you have to be against an idle-timer that removes heroes from the game?