The key point is that Type 2 is caused by too much insulin in the body, so taking drugs to increase insulin or by injecting insulin you are making things worse, not better. Since 90% of type 2 diabetics are either overweight or obese, any increase in insulin which causes further weight gain can result in a higher risk of long term complications and shorter life expectancy.
Actually in the early days of T2D, the insulin resistance stops glucose being burnt off in the muscle tissues, and it congregates in the bloodstream, leading to possible DKA. The insulin resistance ALSO puts up barriers to the glucose being stored in the same cells (for future use) so actually one symptom of T2D is weight loss, not gain. So yes, one way of treating T2D is to flood the body with insulin to force glucose past the IR barriers so it becomes usable and storable again. Whilst this is a bad policy long term, it does prevent the deadly DKA, so saves lives. Ultimately the pancreas goes into burnout, and then insulin becomes totally necessary. The weight that glucose 'puts on' due to storage is a mixture of glucogen + water, and so when we cut carbs and glucose by diet then we lose weight due mainly to water loss. This plateaus out but is not the real cause of metabolic syndrome, which is actually caused by storing lipids in the liver and adipose cells.
This lipid fat storage is often forgotten in the rush to reduce glucose levels, but the process also needs insulin for storage to occur, Thus T2D using meds to increase insulin to lower bgl are also promoting weight gain, especially around the midriff (a typical T2D profile), This increase fat around the liver and midriff in turn seems to make the IR worse, giving the NHS mantra that T2D is irreversible and progressive.
But people like Jason Fung are showing that LC diets and fasting are a valid means to reducing the IR, and lowering bgl without meds. Not everyone is able to come off meds completely, but many find they can significantly reduce their meds portfolio, which can lead to a sort of resolution. I am resolved, but cannot give up all my meds.