Could PC local files be linked to Spotify's own servers?

[knewgrass]

Plan

Premium

Country 
UK

Device

Google Pixel XL2

Operating System

Android Pie & Windows 10

 I have 10's of thousands of music files on my pc and in an ideal world it would be great to access any of them from my phone or any of my mobile devices, but if I understand the current way of doing it I have to create a Playlist of my local files on my pc and then sync that to my phone by downloading them all. That's impossible, as my phone will never have that sort of memory, I'm talking Terrabytes.

Something in the back of my my brain tells me that when Spotify first introduced Local file playback it wasn't necessarily the actual files on the pc, but files on their servers that were linked to, if the song/album wasn't on the server then your local file was used. I could be completely wrong of course but it does beg the question;

Why not just link your pc's local files to the Spotify database, so any songs that are in the playlist can be listened anywhere via streaming and not just via downloading them?

After all I could just manually transfer the songs to my phone and use the inbuilt player (if I had the huge storage).

This isn't a moan or complaint  just wondering about the possibilities