Yet I shipped two in-house ARM designs that licensed the architecture and not the main implementation. We did license some modules that you generally need to make a working ARM.
That said, RISC-V International gives you a spec, and isn't selling you an implementation. Where as ARM Holdings plc does both, with most vendors opting to license a design and adapt it to their needs. But Nvidia, Qualcomm, Apple, and of course DEC have shipped custom or partially custom ARM chips.
Architecturally RISC-V is quite MIPS-like, but organized better for adding extensions. The aarch64 instruction set is a little more MIPS like and less ARM-like than its 32-bit counterpart. (XZR/WZR being kind of like $zero, and the removal of shift operations that leaves behind a big ARM heritage).
The interesting part for ASIC and embedded processors is that RISC-V has a reasonable system for vendor extensions. Allowing one to add some custom instructions or to implement an extension on a lower end core that helps it compete with a higher end configuration. The vendor instructions are always a bit of a compromise and make the tooling difficult. Thankfully it occurs less often, as there are quite a few standardized configurations now. (I maintain a small rv32 emulator that can do a few configurations, it can do accurate single-precision floating point, but it has to fake the double-precision stuff with the host's hardware. good enough to run a typical program but not good enough to get golden CRCs for simulation)