I agree with Henry to let the itch app download things platform agnostic like it used to.
Wine lets me play pretty much everything windows can and Lutris allows me to sort and categorize them very easily for future use.
By letting us download with the app I can update the games through the app swiftly and play them through Lutris.
Right now I have to manually download every update from the Itch website which just makes me not use the app at all whereas I used to use it all the time.
Also most things made were+are for windows, even if a software/game gets a port it tends to be outdated compared to the latest windows version. I would rather not count on people suddenly becoming interested in porting their projects to linux or mac.