From Bungie's perspective, the decision was probably made from a "player experience" point of view.
Imagine a casual player wanting to jump into a Heroic raid. They probably think "hey I'm alright at this, I got matched with a decent group in the normal raid, I got carried a little, I can do this Heroic version", then matched against a group that wants to finish the Heroic Raid ASAP.
That less experienced player would obviously die a few times, the party would need to wipe, and it would be completely opposite of what the group was looking for. Imagine what this would eventually lead to.... imagine the language and verbal punishment that player would receive.
Even in Destiny 1 LFG, I have seen countless people say "I'm experienced, I've done Heroic many times, easy, send me an Invite" and then just expect to be carried. When that person dies numerous times, and the party realizes he just expects to get carried, the verbal abuse is insane.