Sure, some use case will always require the highest single thread perf at all cost but that's less and less true these days.
The dynamism, on the other hand, is a way to issue (possibly) out of order commands when they are ready to be executed (their inputs are ready and no write conflicts detected). For this you need a scoreboard (which is also needed for speculative execution). Scoreboards are for registers (which one is ready, etc) and for commands (which one is eligible for execution). As you can easily assume, these scoreboards are bit vectors, not some interesting thing that maps 80 internal registers to 16 externally accessible register indices.
The scoreboarding in CPUs have long history. They were used in Burroughs' CPUs long ago. They were used in early Alpha AXP designs (first one or two, I guess). They are very easy to implement - yours truly is guilty in this, having done that in month and he is not even a hardware designer.