I stared at Valve's statement restricting the in-game power of coaches, in the way I imagine an archaeologist examined hieroglyphics to gain insight into the lives of ancient Egyptians. A week later, I came to the conclusion that the rule doesn't do what Valve hopes it does.
It came down to three arguments from Valve:
This should be a 5-one-5 competition;
This will improve the majors/minors system;
It will help new teams rise to the top.
The thing is, Counter Strike: Global Offensive is different from other team-based esports. Every CS:GO game can be cut into two halves: offense and defense, with each side partitioned again into 15 different rounds that feed into the next. If the goal was to put it in line with other esport titles, then a better system would be to allow coaches to talk during freeze time as well.
If the actual goal is to be a pure 5-on-5 game, then Valve should ban all coaches from helping, as well as audiences at events, since the crowd has a "sixth-man effect" on a team.
As to how this helps the major system? I don't know. From a spectator standpoint, you lose out on a coaching narrative, the level of competition is worse and you lose out on unique teams that are built around good in-game leading coaches.
So does it help new teams reach the top more easily? No.
Even in the current top tier of teams, having the coach as an in-game leader isn't a clear tactical advantage. Here's a list of the current HLTV top 10 teams: SK, VP, G2, Na'Vi, Godsent, Ninjas in Pyjamas, Liquid, mousesports, Astralis and EnVyUs. Out of 10 teams, four have in-game leaders who are coaches: Na'Vi, NiP, Liquid and mousesports.
The best three teams in the world don't have a coach as an in-game leader. SK is an example of a new team that didn't have a coach, and eventually went on to be the best team in the world despite numerous other obstacles, including lack of money, tournaments and infrastructure.
The CS:GO scene doesn't mirror Valve's statement; in the end, a coach isn't what differentiates a top team from the rest. It tells us the opposite: A worse team can make up the difference with a coach. One example is Liquid's run to the major finals thanks to Luis "peacemaker" Tadeu's shot-calling.
If the purpose of this rule was to help new teams gain competitive parity against the top teams, then this rule does the opposite. New teams are generally built around skill. What they lack is cohesion, experience, emotional control and good comms. A coach as leader can fill in those gaps. Without a coach, the longstanding team will have a distinct advantage.
The more I think about this ruling, the more it doesn't make sense. It worsens the viewing experience, doesn't explain or enforce the 5-on-5-only rule and doesn't help new teams.