If blocks are too big for you to store, then sure you can prune, but that doesn't stop you from having to download them all and verify them all in order to reach the chain tip in the first place. And you have to download them from somewhere. If it becomes so uneconomical to run a full node that only one or two mega rich individuals do so, then that becomes a big problem for decentralization.

Pruning also does nothing to address the issues with the mempool or the fee rate as discussed above.