Nonsense. In fact downtown development will encourage expansion elsewhere.

Seattle's skyline headed upward.

From downtown residents who want more neighbors to developers trying to build to environmental groups fighting sprawl, there's been widespread support for funneling residents and jobs to the city's core in taller buildings.

That can help spare farmlands and single-family neighborhoods from development. (italics added)

The nonsense is in the editorial comment in a news article (but stated as fact) that building higher in downtown will "spare farmlands and single-family neighborhoods."  (Is the reporter so unfamiliar with the subject as to accept political spin as fact?)

In fact quite the opposite will happen. Larger buildings with more people & activity in them will (if the street-level is designed correctly -- that's the key) make downtown Seattle more interesting, comfortable etc and will enhance the entire region's overall attractiveness. A truly urban and urbane CBD will increase Seattle's global prominence. It will draw yet more business and people to our region, thus increasing demand for new space of all types in every part of the region.

(And I am not even going to get in this post to the fact that the CBD housing market and the suburban one are very different and serve a different part of the human life-cycle. With rare exceptions, there is no substitution of downtown condo for detached dwelling i.e. the idea of  "family-friendly" housing downtown in a chimera.)

(Mind, I am not aware enough of the specifics of the zoning changes to be for or against them. In general I share the City's goals; I am all for more development downtown, though I think the impact fee aspect is typical cheapskate Seattle ""Who me? Someone else should pay." Subsiding affordable housing is a good idea? Yes.Then why should buyers of high-density housing — arguably doing the right thing from an environmental perspective — have the burden placed on them? Typical sanctimonious Seattle BS: find the nearest target of opportunity and exploit it. If subsidizing housing for defenseless populations — not "affordable" — is a good idea then all of us should take part in funding the subsidy.)

But it is the connection between downtown development and growth elsewhere which is the fallacy. It's dream world to believe that in any but the most marginal & remote way new construction downtown will lessen demand for new construction in other areas of the region, especially when it comes to housing nuclear families. It's good to have a vibrant downtown for many reasons but the major one is simply to have a vibrant downtown.

There is too much pool-playing, looking for caroms and ricochets, and "gaming" going-on. Just do the things you want because in themselves they are beneficial — here a walkable, cheerful, comfortable CBD — and not because of some second, third, and fourth level impacts which you hope to instigate by clever finagling. In this case, as I say, making the core neighborhood of the region — Seattle's CBD — more interesting makes the region more interesting and thus actually promotes development everywhere. Ironic. Some would say a "damned if you do or don't" situation. There is truth to that if you don't like growth. It's Annoying. Frustrating. But it's the way real estate works. Good planning provides (or should) a "context of certainty" within which people can make large investment decisions. "Really good planning" actually makes an area more desirable and hence promotes growth. Ironic indeed. (Btw, I am not suggesting that Seattle has had, though with some notable exceptions, such really good planning.)

But some folks buy into the fantasy.