Sweat is mildly acidic and goes everywhere
On bare or painted concrete it soaks in and stays. No amount of cleaning the rubber above it addresses what has absorbed into the slab. Coating first means sweat stops at a non-porous surface you can lift a mat and mop, which solves the smell problem permanently rather than managing it.
It also stops the grey
Bare concrete dusts under the movement of rubber mats, and that dust migrates up through the seams. It is why gym rubber looks grey and tired after a couple of years. A sealed slab underneath keeps the rubber looking like rubber.
The coating protects the slab, the rubber protects the coating
A dropped 45 lb plate on its edge is a concentrated impact that will chip any coating and can spall bare concrete. The coating is not meant to take that, rubber over it is. Use 3/4 inch minimum for bumper plates and a proper platform for heavy lifts.
Cleaning products matter
Gyms get wiped down constantly, and some quaternary and alcohol-based disinfectants dull a polyaspartic topcoat over time. We hand over a compatible-product sheet. A small thing that keeps the floor looking new for years longer.
Want this answered for your slab?
Free site visit with a moisture reading, then a written fixed price. Across the BC Interior.