no.
But OneDrive needs individual synching of files, and having said that, it needs an option to always download a folder and all the files inside it, so you don't need to download files everytime they are uploaded somewhere else like happened with Windows 8.1.
Placeholder were a crappy implementation and if you had many GB uploaded, they would consume alot of space even if you didn't need to see all OneDrive files.
But maybe it would be useful if they made something like placeholders but more like shortcuts, so they don't take space and really, they don't act like real full files that can cause a program to crash because when the program tries to open them, the files are not valid, since they are big and don't get downloaded quickly.
Sometimes I remember on 8.1 I double click on files believing they were available and the software said it was opening them, but never happened, and program froze and in the end it took minutes and minutes and nothing. in the end I had to go and make them available on OneDrive's folder, manually, reopen the program or double click it and keep working.
But I think having all OneDrive files structure displayed would be good so for example you can move files on OneDrive website and still have them downloaded instead of deleting the files off your computer because they are not checked on synched folders option like happens with Windows 10.
so I don't miss placeholders but they have to work really to make it a really great and better service for everyone's usage, like options to download files individually, or folders but don't download files that can be uploaded in future like OneDrive root folder, or an option like windows 10 that always download a folder and files and future files uploaded to it, so important folders are sure to be up to date unlike Windows 8.1.
So in my opinion, I think the idea of Placeholders idea should be thought more and not just give us that crappy implementation from 8.1 that was only useful with images formats and consumed alot of space.