> Except pretty much everyone agrees, even within Labour, that Corbyn was unelectable... in part because his team and policies where squarely on the far left.
That does not make of him a bad politician (he can be, but you keep saying "he is a bad politician because I don't like his ideology and his ideology was not popular enough", which is NOT a criteria to decide if it's a bad politician or not). In a democracy, every ideology must be represented, even if they don't correspond to the majority and are therefore unelectable.
But again, that is not my point: Corbyn was shit, unelectable, whatever, ... And yet, the other party had bad politicians. Corbyn is not the one putting those politicians there. Corbyn supporters neither. Neither Corbyn or his supporters have any say in this, because they have a different ideology and therefore cannot build a good-politician party that defends an ideology they don't agree with.
The fact that the restaurant A serves expired food is not a good excuse for going to the restaurant B, eating slightly less expired food, pay your bill, leave without complaining about restaurant B, and conclude that the main reason is that restaurant A was bad. Restaurant A is bad, and we can, and should, complain about it, but when there is an article about restaurant B explaining that they are failing to serve correct food, you cannot bring in restaurant A as an excuse for the failure of restaurant B. The MAIN REASON restaurant B serves bad food is BECAUSE RESTAURANT B IS FAILING.
You may even be centre-left and chosen Tories for the first time just because you did not like Corbyn. But as soon as you vote Tories, the quality of the politicians in the Tory party is YOUR RESPONSIBILITY. If you vote for them, you are part of the process that reward their choice of bad politicians. (I use "you" as the "hypothetical you", not you in particular)
Also, your idea that what matter is the electability is really bad for democracy. Basically, it implies that minorities should never be represented.
> A healthy democracy needs a credible opposition.
If your definition of "credible opposition" is "an opposition that I would have maybe voted for", you are dead wrong.
In a healthy democracy, when you have two main parties, one in power, one in opposition, then, there is one party that you should think is okay, and one party that you should think is shit (it's more complicated than that, but it is to illustrate). If you like all the parties, it just means that you have just one ideology represented.