I've never heard this being proposed- most vertical farming startups with any true prospects tend to be just outside the cities, but substantially closer than other farms. The chief advantage in vertical farming has nothing to do with actually farming within a city and everything to do with shortening supply lines. Likewise, I've never seen any company propose that they could completely replace conventional farms, but it's worth noting that every crop that can be grown with vertical farms allows another crop to be grown on arable land.

Short supply chain: If I harvest in the morning and drop produce off in the afternoon to a restaurant or sell at a farmers market.

Regular supply chain: especially with large corporate farms. Harvested and hydrocooled(in case of greens) within 90 mts. Transported to cooler. Goes to packer and wholesaler. Distributor and broker and then onto shelf space at supermarket. It’s alreadr 3-4 days old. Expensive with fossil fuel based storage. Being transported. Could go into trash as food waste if it isn’t in pristine condition. These are the costs of longer supply chain.

With tomatoes etc that can bruise when ripe, they are picked unripe and then given the ethylene treatment for ripening.its several days old and needs a lot of $$. And energy wasted.

Why would you say short supply chains don’t save anything.

It doesn't save time? Oil? I don't understand your reasoning here.