Test fires with a near-empty rocket would put considerably more force on the pad's hold-downs and the corresponding parts of the rocket's structure.
Blue also had a fuelled 2nd stage on top of the booster for the static fire, which is not out of the ordinary.
SpaceX has a "cap" that is held down with cables that it uses when it needs to test-fire a first stage by itself at its McGregor test site; static fires at launch sites are usually done with the 2nd stage on top.
If you want to argue that it's impossible in practice, I'll point out that SpaceX's Starship first stage has a net thrust of 53 MN [3], and it does static fires (without the weight of the second stage on top) [4].
The space shuttle didn't do static fires because of the solid rocket boosters that would need to be teared down and reconstructed afterwards; not because it's physically impossible to hold it down.
[1] https://en.wikipedia.org/wiki/Space_Shuttle
[2] https://www.unionfab.com/blog/2024/03/yield-strength-of-stee...
Off the top of my head, I recall in SpaceX's case it was a helium tank failure- a helium tank weld failed and the helium tank itself shot through the cryogenic oxygen, hit the far wall, and gave off a spark. But that sort of failure is only apparent when everything is pressurized correctly, which means tanks have to be full. The goal of the test is that you detect that sort of failure before it goes boom and then can fix it.
https://www.youtube.com/watch?v=_BgJEXQkjNQ is a video of SpaceX's failure.
Quoting from one of the press releases:
"The recovered COPVs showed buckles in their liners. Although buckles were not shown to burst a COPV on their own, investigators concluded that super chilled LOX can pool in these buckles under the overwrap. When pressurized, oxygen pooled in this buckle can become trapped; in turn, breaking fibers or friction can ignite the oxygen in the overwrap, causing the COPV to fail. In addition, investigators determined that the loading temperature of the helium was cold enough to create solid oxygen (SOX), which exacerbates the possibility of oxygen becoming trapped as well as the likelihood of friction ignition.
"The investigation team identified several credible causes for the COPV failure, all of which involve accumulation of super chilled LOX or SOX in buckles under the overwrap."
https://web.archive.org/web/20170216160231/http://www.spacex...
There's another comment that it wasn't the weld but even if it was the welders would build to spec and "better" (if it's known what better is) only if it's straightforward. There are certainly scenarios where a fabricator could design a better jig or use a more precise process but if the spec doesn't call for it then it's probably not going to happen because there are also the dimensions of time and money that matter as well.
Edit: yes it was https://arstechnica.com/space/2025/05/spacex-pushed-sniper-t...
>Externally, they sent the site director for their Florida operations, Ricky Lim, to inquire whether he might visit the roof of the United Launch Alliance building... ULA told SpaceX’s Ricky Lim to get lost when he wanted to see the roof of their building in Florida.
The FAA letter:
https://cdn.arstechnica.net/wp-content/uploads/2025/04/Space...
Man, the signs were always there, right? I think I only fully realized it in 2018 during the cave "incident".
You've got two large tanks making up the bulk of the stage's structure - one for oxidizer, one for fuel. They have large diameter pipes that feed propellant to the engines. You can't mix the ballast with either the oxidizer or fuel, and you can't feed the engines from anywhere but the propellant tanks...
Doing so risks having to write so much database logic — with all the potential for getting that code buggy as well — that it’s often better to avoid the mock and test the entire system, end-to-end.
This was an end-to-end rocket test.