I don't think you understand the problem they were facing. If they rewrite the backend it would also REQUIRE rewriting the frontend because of how entangled the

I don't think you understand the problem they were facing. If they rewrite the backend it would also REQUIRE rewriting the frontend because of how entangled they were. Whereas rewriting the frontend did not require changing the backend as dramatically. So their choices were: 1. Rewrite the whole thing, all at once, ship nothing for a long time. 2. Rewrite the frontend, ship changes incrementally, then move onto the backend once it's been excised from the tangled mess.