This discussion is bordering to silly. What I recall from discussions on discord was that there indeed was a “chip shortage” problem, the “full” board, as it was originally designed was a challenge (in particular the FPGA). So a redisign was almost needed anyhow. Yes, raspberry pis have been close to impossible to buy at all - BUT - CM4 was the one mostly available all through the troubled times (as I’m sure one can ser from rpilocator.com via archive.org). However, a pistorm board that can accept just about any old raspberry pi is a huge advantage, as many of us indeed have them lying around. So why not.
With the adapter board, it may even be possible to install CM4 on “old” Pistorm and Pistorm600.