Corbyn is absolutely not a tankie, he's a social Democrat.

If you've learn a bit of history, tell me, once capitalism starts degenerating and the left gets kneecap by the center, what exactly is it that happened? What happened when the SPD alienated the KPD and it's own left wing in order to triangulate itself into having slightly more votes?

What you're seeing is party infighting that likely cost Corbyn the 2018 election, and if you think that suppressing the left is going to be a viable tactic as you just need to compromise ever more with the right, I'd suggest opening your favourite history manual to Germany in 1929 :). Because that really, really doesn't end well.