Disagree. You quite often have a fair degree of scaler code in between portions which are embarrassingly parallel. If you don't have a decent scaler core you are destined to be become bottlenecked on them. It's not that different to a CPU / GPU pairing. If one is under powered, it determines the speed of the overall system.
If you look at what a company like Tenstorrent is doing, they are designing high performance Risc-V cores as a side aspect of their main goal of doing array processors. The reason is because they couldn't find scaler cores on the market with enough performance to not bottleneck the system.