Where a technique exists, there is a reason for it. It might not be the best reason, it might not be the most effective or efficient, but there is certain a reason that handling a firearm in a certain way was developed.
Why was the M16 taught to be fired from the hip? It was a holdover from WWI with the BAR and Lewis pushing from trench to trench. Why was pistol shooting taught one handed? The other hand of the officer was expected be directing his troops, who are his main weapon. Another WWI item. Why is manually bolt lock reloading the MP5 the ‘proper’ way even though the AK style loads are significantly faster?
1911 Syndicate and James of Teufelshund Tactical have the answers.
TLDR/W though, it clears many possible stoppages during the load and can reliably strip a round with a single technique. AK load is much faster though, for anyone looking at PCC competition with an MP5.