The pros and cons of systems were acknowledged above. For beginners, the time used memorizing an extensive opening repertoire is better spent understanding general opening principles and working on tactics, tactics, tactics.
Acknowledging them does not address the quote, which implies that beginners should play a system because they can just memorize the system and they don't need to try to understand or even care about their opponent's moves. Knowing a few catch phrases like "connect the rooks" or "knights on the rim are grim" is not actually understanding general opening principles.
If a beginner is playing the London and cannot answer, say, a simple question like "why is the bishop played to f4 before the knights are developed?", then they are not learning anything, and all you are really avoiding is them trying to play Scholar's Mate all the time .
As I mentioned, systems are fine. Telling students to just mimic a position for white without any deeper understanding so they can get to the tactics will work okay for scholastic students that aren't going to ever reach a title, but as I said, teaching them this "shortcut" worded that way just passes the buck on to the next coach to unravel the damage for the players that do get good...
"Okay, I know what your old coach told you, but it's time to go past the London, or, if you want to keep playing the London, then we need to go back to square one and you need to learn the reasoning behind it. You're bogged down at 1300, and you won't go past it until you stop doing what you are doing now."
"But Kamsky plays the London and he's been US champ so many times..."
"Do you think Kamsky just memorized the London without understanding why the moves are made?"
"What about Pogchamps? The coaches there say the London is good."
"Pogchamps doesn't have any good chessplayers, and the London is the easiest way to prepare bad chess players to play a semi-presentable game. That doesn't mean the London itself is bad, it just means it's being misused in this case. The London is not intended to allow you play the opening without understanding or calculating anything."
The pros and cons of systems were acknowledged above. For beginners, the time used memorizing an extensive opening repertoire is better spent understanding general opening principles and working on tactics, tactics, tactics.