It can be if stuff is not placed correctly, Soft pine can also split/crush/move. Not a fan of wood blocks under the jackstand either. All anybody is saying is be safe. When one falls off a jackstand it can move sideways. A bunch of what if's, but shyt happens. If your head is tucked in the wheel well...it might not work out so well.
I get what you're saying but under the crossmember it is safer with wood than steel on steel.
I have several sets myself, a couple sets of 3 tons, full set of 6 tons, and 2 12 tons. Jacks can blow seals suddenly so I don't rely on the jack to partially hold vehicles up either. Properly supported no need for the jack to even be in the way.
The photo only exists as a reminder for me as to which blocks to use to get the height I need hence the jack still being there. Like you, I don't trust the hydraulics of jacks so stands are a must. I'd leave the jack there only for when it comes to lowering. It's entirely superfluous with the stands locked off.
What you saw in the photo looks worse than it actually is. At least in part due to the piece of steel between the jack and block which was an exhaust bracket in a former life repurposed as a load spreader but short of time I didn't cut off the dangling bit that in the photo is between the camera and the jack's threaded extension and makes everything look squint and lopsided. Trust me, I take all of this very seriously.
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