Yes, finally in 2020 Dolphin can open a file from an SMB shared folder without making a local copy, which basically made KDE unusable in any environment that involved editing files on a Windows share.

Took a while but it does work, bar a few minor issues. I have problems with certain applications not understanding Dolphin has already authenticated to a share. For example VLC will only open a file if the URI to the share contains the user name required to authenticate (smb://user@fileserver/Video).