Of course they need to avoid heating up the product that is the reason the scale and density of the chip makes it harder to cool it efficient as it less much less contact to cool it.I think there is something about Zen 5 preventing them from reliably operating at the higher frequencies the (assumed) N4P node could permit over N5, so they get to fully benefit from the decreased power consumption instead. So it is trivial to drop the TDPs on the 12-core and 8-core without sacrificing performance.
As for the lower base clocks, if you have sufficient cooling and a demanding workload, you'll hit higher clocks instead. They have lowered them to flex on Intel in power efficiency charts. This is just a theory. It could be that Zen 5 has major problems, or the press release had incorrect information.
Pumping up the MHZ does not make any product better is you can not cool it enough, hence the 14x00 intel cpu line.
As i already stated before many reviewers advise to go for the 13x00 series as it outperforms the insane hot headed 14x00 series, hence the higher prices for the 13x00 series