I didn't say you were solely responsible for forcing the narrative, I said it is forcing a narrative. Both those articles are guilty of it as well.
You've bolded an extract from the end of a long paragraph about minority partners in coalitions to argue that it says something completely different to what it does say.
You're comparing two parties operating in completely different electoral systems, faced with completely different challenges, and a different electorate to argue for one, one sized fits all solution, and – in doing so – completely bulldozing through the fairly obvious differences between the situation of the two parties.
The SDP are in a mess, no one's doubting that, but it's a mess caused by far similar pressures to those the Lib Dems faced in 2015 (and are continuing to face) than the ones Labour face(d). Shoehorning a narrative about centre left politics on to it is a step too far (and besides there's better examples of that phenomenon happening in Europe than Germany, for my money).
Besides, the whole post starts off under the flawed assumption that those that want rid of Corbyn want Labour to return to the left of centre, which doesn't necessarily follow. I'd like Corbyn to go, I think, but I'm happy with the direction he's taken the party in; I'd just prefer him replaced with a pro-EU candidate that doesn't have to spend most of his time fighting a string of self inflicted PR own goals. That person might not exist in the Labour party, but a man can dream.