It's not that weird; Stronglifts (SL aka 5x5) and Starting Strength (SS aka 3x5) both utilize progressive overload to stimulate gains.

Progressive overload works. Those programs "work".

They are just out of vogue for beginners, and they are both targeted towards beginners.

Out of vogue for beginners according to what/who? This is the first I'm hearing of a falloff of 3x5/5x5 for beginners, so I'm confused where this is coming from.