When a policy has lasted forty years across both parties' having periods of absolute governing power, one can't really pin a policy on a single party anymore.
Your point makes slightly more sense if you're talking about the US instead. I still think it's silly to ascribe equal blame to the instigators of the idea and a party that fails to push the tide the other way because of inertia and political expediency.
I mean the centre ground if fucked over there, so you have my sympathy.
It's not inertia, though. The Dems have had the power to make meaningful change several times in the past four decades. Their failure to do so is a choice they've made repeatedly.