I personally think that this left-right conflict within the party is overstated as an unending philosophical battle - the problem the PLP, and those within the wider party who don't like them, have with Corbyn and McDonnell, and Abbott and Milne et al is far more personal than that: they don't like their dodgy friends and suspect allegences, and they certainly weren't going to take an imposition of party discipline from people who'd spent the last 30 years voting against the Labour whip and decrying those who did not.
Someone like RLB is certainly going to face opposition over this or that policy - just like any party leader in parliament - but they wouldn't face the kind of visceral hatred that Corbyn and his generation of the parliamentary left aroused. Simply put, LB, Rayner, Lewis and the others weren't friends with hostile regimes or appeared on their propaganda channels, nor did they consort with or praise people who were killing British citizens whether at home or abroad.
You do sometimes have to question the emotional intelligence of those endlessly prattle on about systems, not personalities....
Ah, but many of them came of age during the STWC era, maybe they shared platforms with some dodgy radicals?