Proton is mostly just wine and esync has been replaced by fsync a while back. Ntsync is another even faster/better sync mechanism.

Ntsync is much more capable than fsync, which was the replacement for esync. Many games that benefitted from esync will benefit much more from ntsync. Esync also breaks many games, which ntsync seemingly does not.

Also, the majority of people running games on Wine are doing so with a version of wine that includes fsync. Lutris, Bottles, and Heroic all support versions of wine with these patches.