Whatever the case the Aircraft fell due to a combination of a smart AA commander, ineptitude of mission planning, Dumb luck of a door failure and poor weather at the SEAD base, and the aircraft lacking Radar warning/missile warning countermeasures. Something more modern aircraft would have from day one. Farther the B21 is likely to be far more networked than B2 ever could have been. Making it about as much a hot rodded B2 as a comparison between a modern IPhone and a Brick cell phone of the 1980s.
You're missing his point. The F-117 was shot down because at the time the USAF felt its stealth capabilities meant it could operate in Serbian skies with impunity, when it clearly couldn't. The Serbs found a radar wavelength that could detect it and the rest is history.
The same thing could happen with any iteration of stealth, be it American, Chinese or Russian. No matter what stealth is deployed it will always be detectable by some wavelengths, even if it is thermal, optical, etc. All an enemy needs to do is adapt to the new technology which in all of happens eventually.
Talking about how amazing the B21s stealth is and how much better it is to the F-117 will only lead to the same hubris that existed before the F-117.
Talking about how quickly the B21 came out is also American arrogance. They've unveiled a non flying model to the public. It's still years away from being deployed. It may well be made of plywood like the Russian and Iranian stealth planes.
If anything the opposite is true. Planes take longer to induct now, look at the F-22, F-35. While CAD and computer modelling has improved, planes have become a lot more complex. A lot of the new technologies involved aren't suitable for production line manufacturing and assembly, so they still need to be manufactured by hand.
Funding is also a much bigger problem. In WW2 you had planes being deployed within a year of them being on the drawing board.