When the segregation between Group and Solo queues was originally implemented, MWO was running with a version 1.0 matchmaker without all the bells and whistles we have today. New players were running up against groups of 8-12 players in coordinated builds on teamspeak together and getting facerolled. No one wanted to keep playing when they knew they could drop into a match only to see 12 AS7-D-DCs rolling up over the ledge in Frozen City.
There is no longer any real danger of this happening today.
With the implementation of 3/3/3/3, it is no longer possible for large groups to strongarm their way through solo players and smaller groups by throwing 12 Assaults or 12 Lights at them. Even if one team contains a 12-man and the other a smattering of smaller groups/solos, neither team will be vastly outweighed by the other.
Likewise, the successful implementation of in-game VOIP has negated the tactical advantage of groups being able to communicate via Teamspeak. Now, anyone can call targets or spot enemies without being forced to type while dodging autocannon rounds.
Most importantly, the implementation of PSR will help dramatically with ensuring that teams consist of players of roughly equivalent skill levels. This means that brand new players won't be running up against large groups unless those groups, themselves, consist of players with approximately Tier 4 ratings. On the other side of the coin, it also means that Tier 1-2 players who drop solo can be used to fill in gaps in Tier 1-2 teams which lack a full 12.
Removing the restriction on group/solo queues is the best way to ensure that the matchmaker has the largest possible player pool to draw from, resulting in the best possible matches for everyone.
Edited by Vlad Ward, 21 August 2015 - 10:18 PM.