There's a youtube channel by a guy who ran/runs an Apple-affiliate repair shop. He has definitely seen storefronts remain idle for multiple years. I see this happen in my local area as well and don't understand it.
That may be a factor but it’s not the primary cause. This has been going on forever because commercial leases are usually 5-20 year commitments.
I’ve danced the dance with many landlords where they act interested in having you lease, but clearly your business isn’t what they consider a “good tenant” so they draw things out while they continue to look for a “better” tenant.
The empty spots in the city do speak with prospective tenants but often have unrealistic requirements for small companies and unrealistic pricing. Beyond the rent you may be required to have seven figures liquid to be in a position to secure a lease. Especially for a restaurant. Especially if there is a buildout.
Things get a lot easier if you can take the space as is. But even then, if the landlord thinks your business is at a high risk of closing within a year, what’s the point? Why not spend most of that year finding a secure tenant likely to last for a decade or more.
This leaves many empty stores in Manhattan.