Okay, hypothetical from someone with an advanced degree in Economics, not because I'm bragging, but to save you the snark and insults:
Developer gets the green light to demolish 30 unit building and build a large high rise at say, 6th and Howard. Many of these people are on the lowest end of the income spectrum.
So you demolish the units and build a 150 unit, 15 story luxury apartment building, because you know Square is a block away and their employees can afford to pay ridiculous rents. As the owner of the building, how many units are you building to occupy the old, lower income tenants, and how many are you building to occupy the Square tenants, who will often be able to afford 3x the price?
This is the problem the article is pointing out. No matter how you build "more housing", it very certainly will be first built for the highest income people, thus pushing the lower income teachers, firefighters and policemen, out of San Francisco proper.
Clearly your "advanced degree in Economics" hasn't taught you any common sense.
Is anyone saying that the housing that is built first has to go to lower income people? Is anyone saying that you cannot just build more housing? Do you understand that there is not an infinite supply of tech workers looking to move into expensive apartments?
I mean, assuming we're not talking about putting in 500,000 new units or something, Stalinist-apartment-blocks style: that would really produce enough supply to soak up any excess demand (which was precisely the point of Stalin's building programme). And their unattractiveness might reduce demand, too...
Based on what exactly? I don't think you can compare Manhattan to SF in this regard. Manhattan has general appeal and is well-known worldwide, whereas this issue with SF is specifically due to tech workers.
And I am not convinced that there are so many tech workers that you cannot accommodate everyone else as well. They definitely aren't going to be "pushed out of SF" if you allow high rise construction in all parts of the city.
Anyway, all those theories are fine, but I don't believe the development that could physically be done in the next 3-5 years would outpace tech employees and I believe that it would, as the article says, push lower income SF residents out. This is the entire point of this article, and seems to be going over your head. Not to mention that the article actually addresses the idea of building high rises all over and talks about how poorer high rises will be crime ridden while the upper class high rises would push all the locals and culture out. But hey, why use common sense or rational thought or even bother to read when you can just act like an insufferable condescending asshole? Really, I'm never usually this harsh on people, but your path to "winning" an argument, seems to be hearsay and insulting people versus logic and reason. Fuck that.
Also, I don't think if someone demolished a lower-class apartment in SoMa they will do anything but build the highest cost apartments (If your options were to build apartments that cost $1500/mo for locals or $3500/mo for new tech employees, which would you build?) and push those lower income people out, which is basically the problem we are discussing, so no, I don't agree with the above assertion. Sounds good in theory, wouldn't work that way in practice.
Moreover, I don't agree with the restrictions on high rises to SoMa. Why not allow them to be built elsewhere? And who says that you have a right to live in SoMa anyway? If it were allowed, high rises would go up in other parts of the city, and you could live there instead.