and how it prob isnt that kind to artists who dont easily fit...

i think the basic answer is more that dangelo, lauryn, etc, they just got uninspired

the movement that gave them so much momentum, ie hip hop culture, basically died, and without that, they no longer had the rudder they needed

and then they fell off

obv the way hip hop died meant that artists like them were less welcome but i think equally, or more than that, its that they just didnt have much to inspire them anymore, nothing 'real' or 'current' that they could feed off