What is the mismatch between SVP and KodI internal player tech?

What technology is it that prevents SVP from being used along with the internal Kodi player?

I'm running both Windows and Linux for Kodi, in Windows I use DSPlayer, i.e. DirectShow, and on Linux I can get SVP to work with mpv as external player.
I would love to run Kodi solely on Linux, but using mpv disables all OSD menus, so I can't download subtitles etc via the OSD = no go.
Windows however works, but its Windows so... eh..

Basically I'm just wondering whether the internal Kodi player will ever be compatible with SVP so that the whole setup of Kodi + SVP will become platform agnostic?