This is why cubicles are a thing though right?

Obviously it doesn't have as much in terms of sound dampening effects but the cost nearly isn't as high and there's a psychological effect

Though... cubicles do make it so that you're working in a "pit". So people... start wanting to remove the barriers..... and we end up in open office plans again. Hard to figure out how a smaller company can manage this (since private offices _are_ expensive)

Back in days, each engineer in Microsoft had a private office. Oracle too... Good days...

Some buildings in Microsoft still do. In my building, most people SDE2 level and up has their own, and below that most seem two-to-an-office (there are counterexamples on both sides though, as well as a number of empty offices). Oddly they're refurbing existing buildings to remove the private offices though. It doesn't seem like a space problem, nor a money problem. Apparently there's just a desire to get rid of them for who knows what reason, spending a lot of money and morale (employees have to relocate to temp offices in downtown Bellevue for a year while they refurb a building on campus) to do so.

When I was moved from single offices to open plan (Microsoft 2012) we were told that we had asked for it(!)

But the architecture firm who designed the space did give a really good walk through of how they designed the space. All their stupid decisions had justifications. One tidbit that fell out of that was that they couldn't put more people on a floor with open plan because the width of emergency stairwells dictates the floor occupancy rating.

So we lost offices, whiteboards, bookshelves, couches, and privacy. There didn't seem to be much gain

I interned at Microsoft this summer and had my own office.

Yes, they'd give you all the resources you wanted, because they had tens of millions in R&D funding. https://goo.gl/iHb698 (vintagecomputing.com)

Actually remembered that my university had this two, though most people were two to an office so you coordinated to do meetings. And the PhD students were more like 4-6 to a room.

I got my own office as an intern at Oracle a couple of years ago.

Is it really? In some of the past threads people have posted estimates that the increased floor space would cost a small fraction of salary even in SF. I haven't checked this because I'm not in a position to decide (except by turning down open-office jobs). It seems plausible that the real expense is in converting to a real-office setup instead of any raw packing inefficiency.

Why not let them work from home and save even more then?

This sounds like the critical question in the whole thing.