Yes, but the reduction for a desk is only if you don't have another usable surface, and even then it's only a tenth of "lots of money" because a desk is so much smaller than a room.

A tenth of lots of money is not all that much, and very likely cheaper than commuting.

- a 2'x3' area on a table, anywhere in the place you live

For a lot of us (at least for me and some others), a suitable work from home environment includes

- a 4'x3' desk (or larger, for multiple monitors)

- a door or other way to separate the workspace from house interruptions (and vice versa)

- a bookshelf and other miscellaneous items

- good lighting

In general, all that ^ is necessary to be as effective as one would be at an actual office, and generally means a separate room in the house/apartment; and that is fairly costly. The last time I did the calculations, it came out to several thousands of dollars per year.

Whether you can get a nice isolated place depends on the particular place you're living.

But I was never arguing that isolation isn't necessary! Please look again at the initial comment I replied to.

"Either you paid for more space or you lost space at your home during the 8 hours you were previously working at an office."

My concern was only with the second half of that "or". To get to the second half of the "or", you have to take it as given that there's a suitable spot in your home. When you argue that many homes don't already have such a spot, I agree, but that's irrelevant to what I was trying to comment on.

Everything I've said here should be interpreted like this: "Okay, so you've decided you don't need an additional room? Well in that case, I don't think the space taken up by working from home in an existing room is a big deal, because xyz."