Offsets are better than nothing, but they're not sustainable. Low-hanging fruit will be used up at some point, and actually removing CO2 from the atmosphere is really expensive (most optimistic figure I've seen anywhere estimates $50/ton for the mid-to-long term). So the incentive is to push for actually zero emissions instead of net zero.

And as sibling comment mentions, climate change is bad for business too, so that's the incentive for net-negative.