Why does PPSSPP emulate the PSP operating system?

[VIRGIN KLM]

The only usefull thing out of the whole PSP Bios are the fonts (and possibly a couple of modules) that PPSSPP have for both cases substitutes for them that makes zero change at all.
LLE Emulation for the whole hardware is like an insane project, which would render the name "PPSSPP" pointless since a high end PC would barely be able to emulate games at anything over 1-2fps, let alone Android phones.
Partial LLE emulation though for the ATRAC3+ decoder though could be possible but it's not going to happen since nobody knows anything about the hardware that does this job plus ATRAC3+ reverse engineering is an easier task to do than doing this.