Hovis builds a garden office*

Yes,
if you've ever been round the Mediterranean, especially the eastern end,
and, coastal Turkey, you often see 'unfinished' properties with some thin steel sticking up proud from the existing structure. I've been told that this conferred some advantage on the builder or owner in that the property was not yet finished, and maybe not yet subject to some property tax or other. Certainly in Turkey, the steel used by jobbing Builders until the major earthquake near Istanbul in the early 2000s was smooth, and laughably small gauge.
Maybe only 4/5 mm diameter and only 4 strands in a column.
So no compression effect as the concrete dried/cured, and typically without sufficient 'cover' to protect the steel from rusting, especially in a coastal environment.
In Turkey, that earthquake did force the authorities to start enforcing Building Regulations, and the used of proper ridged rebar.