At the very least, drive letters do make SMB shares a bit simpler for the non technical folks. T:\MyData is easier for them than \\0010-somehost-win.site1.mycorp.loca\Share01\MyData\
I used to support a group of completely tech illiterate users in construction & manufacturing. Them figuring out T:\ was hard enough, ask them to type in a UNC path into the address bar in explorer and you get "Wtf is file explorer? Wtf is an address bar? Where is the backslash key??"
Then in this hypothetical world you could mount \\0010-somehost.win.site1.mycorp.local\Share01 to /Share01 rather than T: