Having an internal clock greatly reduces the overhead for block propagation, as it would allow for a more forward, almost "UDP"-like, block stream. Nodes are then able to order blocks locally, rather than having to wait for sequential sharing of blocks.

The Ouroboros Chronos paper was submitted in July of 2019. https://eprint.iacr.org/2019/838.pdf

Solana Proof of History went live on Mainnet Beta mid-2020.

In my limited (non-PhD) understanding, both allow for the aforementioned internal clock, but are designed for completely different ledger styles (UTXO vs Accounts). Both allow for great increases in block-prop time.