As I keep explaining.
The employer mandate roughly covers 1% of the entire labor force. That's it. Very few businesses are actually subject to being affected by it. It is an inconsequential and almost useless part of the ACA. The delay was done because those few businesses were having a bit of trouble complying on time for the admin threw them a bone.
On the flip side, the individual mandate makes up 95% of the ACA. Without it, the law falls apart. The insurance industry would be a mess, as well. Their actuaries set prices based on the fact that the mandate exists. Without it, many people will simply not get insurance until they get sick. This drives prices up, enormously. Don't believe me? Look at NY. Their have similar laws to the ACA without the mandate and their individual market for healthy people starts at like $1k per month. Only about 6k people in the entire state have individual insurance as a result!
So arguing that the individual mandate should be delayed a year as reasonable is absurd. Without it, the entire law fails. The GOP knows this and that's why they are messaging it. If Obama delays the mandate, the ACA will fail and everyone will see it fail.
It's a bullshit underhanded way of crippling the law.