gone are the early access days when you'd have to make attacks at a disadvantage. I guess in the end Larian decided it was just too much to ask of new players who had never played D&D to cope with.
It's because they couldn't get it to work properly. Myself and others noticed quite early on that the light/dark mechanics didn't seem to work consistently and sometimes it seemed impossible to get a high enough light level to make the target obscured disadvantage go away, not lighting your weapon, not using dancing lights, not fighting in the middle of a fire puddle, while on fire, with your weapon lit up with the light spell (that one in particular, was an encounter I had).
Darkness in pnp is relatively easy to deal with in comparison, because you don't light a torch, only to have the dm tell you that it's still too dark to see (assuming normal non-magic darkness).