Don't know where you got this wisdom from ...
That a well known US american airplane pioneer and producer I respct highly wasn't able to get his designs working, doesn't mean that other couldn't. The Horten gliders were at their time the pinnacle of motorless flying.
It's motorized versions were as solid as every plane the no worse account of crashes than any other plane (ok, the first version with its too advanced for it time system of turnable wingtips was unstable, but with the "normal" Horten-type airlons arrangements on a fixed wing the were used as trainers ...).
If you refer to the crash of the Go 229 ... I would recommend you reading :
"Horten Ho 229
Spirit of thuringia" by Andrei Shepelev and Huib Ottens, 1st published 2006, ISBN (10) 1 903223 66 0, ISBN (!§) 978 1 903223 66 B
There you will find a proper account of what happend : an engine failure and due to it an hydraulic error causing an untimey deploying of the landing gear. The flying itself was regarded as FUN by the pilots.
True, "Nurflügel"-planes aren't easy to plan build - only that there are dozens of build-your-own-plane kits available worldwide without fly-by wire.
And for the He 162 (sometime called "Salamander", sometimes "Spatz") : There's a good book about it with a lot of post-war allied pilot reports flying her. In short : if you are a soft and carefull with the gas ... TOP PLANE.
However, with perhapd double the time of its development (what would have been still less than a year from first drawing to powered flight) these first illnesses would most likely been erased.
I suggest you read something that is not a veritable love letter to the aircraft.
As I noted, as other have noted, flying wings absent the presence of computer aided control surfaces that can react far more quickly, and in far more variables than any human pilot, are great places to die.
Flying wings be they from Horton or Northrop or any of the many others who looked into the design are terrific, absolute wonderful machines right up to the point where they are not. When they get hit by the unexpected gust of wind, or hit turbulence, or downdrafts or any of the almost uncountable issues that can occur in flight, or when a human pilot makes an error (and human pilots, even the very best, make them ALL THE TIME) and the plane starts to spin or skid in the air they become unrecoverable. The term of art is a falling leaf spin, when an aircraft becomes divergent on multiple axes. Spins along a single axis are generally readily recoverable, in fact part of flight testing is spin recovery. Spins in a flying wing are almost impossible to keep in only a single axis, and if the aircraft become divergent on two or more axes they are impossible to save.
Spin recovery in important in every aircraft, be it a private plane or a cutting edge fighter, but for the warplane it is critical. Combat puts aircraft into situations that the designers never imagined, that the men flying it would never attempt in anything but life and death conditions. Combat aircraft are also extremely likely to suffer damage to control surfaces, making the most stable of aircraft difficult to keep in control. Flying wings are always on the edge of instability, trying to keep one in the air with a four inch ragged hole in the aileron, or missing a trim table, or with a chunk of the leading edge blown away is literally impossible for a human being.
Beyond the basic realities of aerodynamics the best possible demonstration that flying wings, using anything before 1980s technological assistance is that no one made them. Not the U.S., which had the Horten's data, and utterly unlimited funding (the U.S. actually flight tested aircraft powered by nuclear reactors for crissake) nor the Soviets, with the same sort of test data, who would literally try anything, up to and including efforts to control aircraft with thought, tried to revive the concept beyond the wind tunnel.
It wasn't that they didn't understand the advantages that a wing represented, they are stunningly obvious, they couldn't make them work in any sort of testing.
Fans of the Luft '46 designs tend to ignore the fact that the data, not to mention the actual designers was readily available to the victors (that is how Luft '46 could even exist). Those victors then engaged in a decades long Cold War, striving every day for an advantage, spending literally obscene amounts of treasure in the effort. If any of the concepts were worthwhile they were used. Both Horten brother survived the war, one was even a post war Luftwaffe officer. If their designs could have been made usable it would have happened.