Homebrew emulators will almost always work better than first-party ones which need to avoid copyleft code, and can be content with a small subset of games being "playable", or "good enough".
Console makers will often hire lead developers of open source emulators to sew something up for them, like what was used for the mario 35 collection (part of galaxy was recompiled too) or the "ps2 classics" software emulator for the ps3.
