Concur is simply compliance software. It is not a TA, an OTA or anything else. One can set Concur up to permit (or not) pretty much anything that can be booked through a corporate TA. E.g., F, fully-refundable, and so on.
Most people who experience problems with Concur are not experiencing problems with Concur, but rather with their employer's policies or competence or both.
The value to the employer of a system such as Concur is that the travel policy is effectively baked into the software.