4-man room entry with 1 and 2-man clearing corners 1st
is a 1990s technique, that despite not working in real combat,
keeps getting taught as the way to go.
My thoughts on the origins and the flaws with it....

Jeff,

Thanks for the great vid!

What you said badly needed to be said.  Like you I see so many of these CQB videos and just want to face palm.  It is sad to wonder how many servicemen have died using sub-par techniques.  I learned local LEO-style CQB methods early and used them in FOF and my experience and training agrees completely with your assessment.

From reading Paul Howe's books I understand that there was a though that it is simple and efficient to train for one mission (hostage rescue) that can be adapted for everything...  so just guessing that maybe there is baggage from that keep it simple mindset?

If it were adapted with the times sure, but it never was. I was going to mention in video two instances in 2003 Iraq where this tactic had major failures. Both instances despite over whelming numbers U.S. Special Ops took a number of casualties.
1st well known Delta hit on Saddam Brothers, Delta got lit up trying to stack up and go in. After multiple wounded backed off and fired rockets and heavy weapons into house.

2nd lesser known... 5th SFG, two ODAs (24 dudes) against 3 prepared bad guys, they took multiple killed and wounded, Stacking up plates to the front using classic CQB. That debackle lead to creation of SFAUC program. (Only to end up teaching same old drivel).