Why are the emulator rules changed. What were the problems with the previous rules. Also, OBS Studio does not have a way to record the full emulator window.

Because people can abuse the old rules by using faster emulators, and if you can't do a full screen window capture with OBS it's time to download a new version. I made a full screen EMU layout in OBS in less than 60 seconds so...

use the classic OBS

I was told by moderators as long as you show what emulator you are using at some point in the run, it's ok. I did not want to have to download OBS classic so I just showed my entire display at the end of the run.