I'm not sure why this plugin needs to be in a different location.
You might ask Sorayuki for why they install the Multi RTMP Output plugin in there and the DistroAV team why they put their plugins in there, too.
I have tested all installation methods with Sorayuki's installers of 0.7.3.0 and 0.7.3.1. It works fine in the following installation methods:
- Normal install (C:\Program Files\obs-studio)
- User-specified location using an installer
- Steam
- Microsoft Store
The one method where C:\ProgramData\obs-studio\plugins will not work in is an unpacked ZIP set up as a portable install using the "obs_portable_mode" file. If you are using a portable install, you really should not be using plugin installers anyway but using ZIP files unpacked into the appropriate places in the portable install directory.
If you unpacked a ZIP file and did not create an "obs_portable_mode" file at the root of the tree where you unpacked OBS Studio into, it will behave like an installed copy of OBS Studio, looking in the home directory for configs and adding C:\ProgramData\obs-studio\ as a location to find plugins.
That said, I am not sure what to say there, but all I can say is that "It works for me", even in its location in C:\ProgramData\obs-studio\plugins.
--Katt. =^.^=