Managing tenants can be more trouble than it's worth. The people buying up these properties likely prefer security and liquidity more than maximizing their return. Tenants make the building more difficult to sell because they often come with very long leases.

There's also a strategy of waiting for rent prices to appreciate enough before leasing to corporate clients. You could get 10y $1000/mo from a small time coffee shop, or you can wait 5 years and maybe get Starbucks locked into a 10y, $5000/mo lease after the area grows up a bit.