This is extremely common and is a feature.

Without it, suddenly you can hear every conversation happening all the way on the other side of your open plan office. It becomes extremely distracting.

It's a cost saving measure warranted by open spaces. We used to have walls and closed offices instead.

Open plan vs private office is a totally different conversation.

Adding the white noise isn't cost-saving, it costs money to install.

My building has this too. I wear noise cancelling headphones with no music to eliminate the white noise.

There is nothing bad about that. The opposite phased sounds it plays genuinely do cancel out the vibrations from the original noise, decreasing the magnitude of the vibrations hitting your ear drum.

Right. I know how they work. The fact of the matter is that the work space sounds significantly quieter when I enable that “bombardment.”

The HVAC system occasionally stops at my work, in the rare occasion I'm working late in the office, and the silence is profound and divine.

It only lasts a couple of minutes, and it's a frustrating reminder of how fucking loud the baseline office noise is as a result of just the air movement of the HVAC.