It is not as effective as HCl in cleaning concrete, but it is a lot less trouble to mess with for the reasons you state and a few others. Be reminded we have had some complaints on the odors generated from H3Po4 in an enclosed space. The vapors go pick up by central air due to an dumb operational error.
We use H3PO4 in lieu of HCl to clean concrete for the application of Vinyl Ester flooring coverings in open chemical process areas. A lot of reasoning is that there are many crevices where SS piping would be exposed to Chlorides. We also clean concrete with H3PO4 for the application of Furane Cement.
In enclosed areas we use H3PO4 for preparation of concrete for the application of Epoxy floor coverings.